fixes #282 - remote scripts loading

A new `remoteScripts` casper option has been added in order to load
remote client scripts into the page DOM environment:

```javascript
var casper = require('casper').create({
    remoteScripts: ['http://code.jquery.com/jquery-1.8.3.min.js',
                    'http://cdnjs.cloudflare.com/ajax/libs/underscore.js/1.4.2/underscore-min.js']
});
```

@@ -10,6 +10,7 @@ XXXX-XX-XX, v1.0.0
 - fixed [#215](https://github.com/n1k0/casperjs/issues/215) - added a `--fail-fast` option to the `casper test` command, in order to terminate a test suite execution as soon as any failure is encountered
 - fixed [#274](https://github.com/n1k0/casperjs/issues/274) - some headers couldn't be set
 - fixed [#277](https://github.com/n1k0/casperjs/issues/277) - multiline support in `ClientUtils.echo()`
+- fixed [#282](https://github.com/n1k0/casperjs/issues/282) - added support for remote client scripts loading with a new `remoteScripts` casper option
 - added [`Tester.assertTextDoesntExist()`](http://casperjs.org/api.html#tester.assertTextDoesntExist)
 - added `Tester.assertFalse()` as an alias of `Tester.assertNot()`
 - added `page.resource.requested` and `page.resource.received` events

-Subproject commit efdaeb9e092054de1b30fa093ec2cd2435a2d894
+Subproject commit 1e59e47358b1b1f55227460183ff36180dfb245f

@@ -110,6 +110,7 @@ var Casper = function Casper(options) {
             localToRemoteUrlAccessEnabled: true,
             userAgent:                     defaultUserAgent
         },
+        remoteScripts:       [],
         stepTimeout:         null,
         timeout:             null,
         verbose:             false,
@@ -967,7 +968,7 @@ Casper.prototype.initErrorHandler = function initErrorHandler() {
 };
 
 /**
- * Injects configured client scripts.
+ * Injects configured local client scripts.
  *
  * @return Casper
  */
@@ -1021,6 +1022,29 @@ Casper.prototype.injectClientUtils = function injectClientUtils() {
 };
 
 /**
+ * Loads and include remote client scripts to current page.
+ *
+ * @return Casper
+ */
+Casper.prototype.includeRemoteScripts = function includeRemoteScripts() {
+    if (this.options.remoteScripts.length === 0) {
+        return this;
+    }
+    this.waitStart();
+    this.options.remoteScripts.forEach(function(scriptUrl, i) {
+        this.log(f("Loading remote script: %s", scriptUrl), "debug");
+        this.page.includeJs(scriptUrl, function() {
+            this.log(f("Remote script %s loaded", scriptUrl), "debug");
+            if (i === this.options.remoteScripts.length - 1) {
+                this.log("All remote scripts loaded.", "debug");
+                this.waitDone();
+            }
+        }.bind(this));
+    }.bind(this));
+    return this;
+};
+
+/**
  * Logs a message.
  *
  * @param  String  message  The message to log
@@ -1228,8 +1252,7 @@ Casper.prototype.run = function run(onComplete, time) {
     "use strict";
     this.checkStarted();
     if (!this.steps || this.steps.length < 1) {
-        this.log("No steps defined, aborting", "error");
-        return this;
+        throw new CasperError('No steps defined, aborting');
     }
     this.log(f("Running suite: %d step%s", this.steps.length, this.steps.length > 1 ? "s" : ""), "info");
     this.emit('run.start');
@@ -1321,8 +1344,7 @@ Casper.prototype.start = function start(location, then) {
     if (utils.isObject(this.options.viewportSize)) {
         this.page.viewportSize = this.options.viewportSize;
     }
-    this.started = true;
-    this.emit('started');
+    // timeout handling
     if (utils.isNumber(this.options.timeout) && this.options.timeout > 0) {
         this.log(f("Execution timeout set to %dms", this.options.timeout), "info");
         setTimeout(function _check(self) {
@@ -1332,10 +1354,12 @@ Casper.prototype.start = function start(location, then) {
             }
         }, this.options.timeout, this);
     }
+    this.started = true;
+    this.emit('started');
     if (utils.isString(location) && location.length > 0) {
         return this.thenOpen(location, utils.isFunction(then) ? then : this.createStep(function _step() {
             this.log("start page is loaded", "debug");
-        }));
+        }, {skipLog: true}));
     }
     return this;
 };
@@ -1848,7 +1872,10 @@ function createPage(casper) {
                 casper.options.onLoadError.call(casper, casper, casper.requestUrl, status);
             }
         }
+        // local client scripts
         casper.injectClientScripts();
+        // remote client scripts
+        casper.includeRemoteScripts();
         // Client-side utils injection
         casper.injectClientUtils();
         // history

@@ -28,7 +28,11 @@ service = server.listen(testServerPort, function(request, response) {
         console.log(utils.format('Test server url not found: %s (file: %s)', request.url, pageFile), "warning");
         response.write("404 - NOT FOUND");
     } else {
-        response.statusCode = 200;
+        var headers = {};
+        if (/js$/.test(pageFile)) {
+            headers['Content-Type'] = "application/javascript";
+        }
+        response.writeHead(200, headers);
         response.write(fs.read(pageFile));
     }
     response.close();

+(function() {
+    var elem = document.createElement('div');
+    elem.setAttribute('id', 'include1');
+    elem.appendChild(document.createTextNode('include1'));
+    document.querySelector('body').appendChild(elem);
+})();

+(function() {
+    var elem = document.createElement('div');
+    elem.setAttribute('id', 'include2');
+    elem.appendChild(document.createTextNode('include2'));
+    document.querySelector('body').appendChild(elem);
+})();

+/*global casper*/
+/*jshint strict:false*/
+casper.options.remoteScripts = [
+    'includes/include1.js', // local includes are actually served
+    'includes/include2.js', // through the local test webserver
+    'http://code.jquery.com/jquery-1.8.3.min.js'
+];
+
+casper.start('tests/site/index.html', function() {
+    this.test.assertSelectorHasText('#include1', 'include1',
+        'Casper.includeRemoteScripts() includes a first remote script on start');
+    this.test.assertSelectorHasText('#include2', 'include2',
+        'Casper.includeRemoteScripts() includes a second remote script on start');
+    this.test.assertEval(function() {
+        return 'jQuery' in window;
+    }, 'Casper.includeRemoteScripts() includes a really remote file on first step');
+});
+
+casper.thenOpen('tests/site/form.html', function() {
+    this.test.assertSelectorHasText('#include1', 'include1',
+        'Casper.includeRemoteScripts() includes a first remote script on second step');
+    this.test.assertSelectorHasText('#include2', 'include2',
+        'Casper.includeRemoteScripts() includes a second remote script on second step');
+    this.test.assertEval(function() {
+        return 'jQuery' in window;
+    }, 'Casper.includeRemoteScripts() includes a really remote file on second step');
+});
+
+casper.run(function() {
+    this.options.remoteScripts = [];
+    this.test.done();
+});