re #138: oembed: enable crossdomain AJAX for IE

Author: Jaza

dist/js/medium-editor-insert-plugin.js

@@ -782,7 +782,11 @@ this["MediumInsert"]["Templates"]["src/js/templates/images-toolbar.hbs"] = Handl
     Embeds.prototype.oembed = function (url) {
         var that = this;
 
+        $.support.cors = true;
+
         $.ajax({
+            crossDomain: true,
+            cache: false,
             url: this.options.oembedProxy,
             dataType: 'json',
             data: {