fixes #92 - form submit fails when form element doesn't have method field

@@ -517,7 +517,7 @@ Casper.prototype.fill = function fill(selector, vals, submit) {
     if (submit) {
         this.evaluate(function(selector) {
             var form = __utils__.findOne(selector);
-            var method = form.getAttribute('method').toUpperCase() || "GET";
+            var method = (form.getAttribute('method') || "GET").toUpperCase();
             var action = form.getAttribute('action') || "unknown";
             __utils__.log('submitting form to ' + action + ', HTTP ' + method, 'info');
             form.submit();