Remove some `Ember.Deferred` usage. It's deprecated.

app/assets/javascripts/discourse/lib/utilities.js

@@ -313,14 +313,14 @@ Discourse.Utilities = {
     @method cropAvatar
     @param {String} url The url of the avatar
     @param {String} fileType The file type of the uploaded file
-    @returns {Ember.Deferred} a promise that will eventually be the cropped avatar.
+    @returns {Promise} a promise that will eventually be the cropped avatar.
   **/
   cropAvatar: function(url, fileType) {
     if (Discourse.SiteSettings.allow_animated_avatars && fileType === "image/gif") {
       // can't crop animated gifs... let the browser stretch the gif
       return Ember.RSVP.resolve(url);
     } else {
-      return Ember.Deferred.promise(function(promise) {
+      return new Ember.RSVP.Promise(function(resolve) {
         var image = document.createElement("img");
         // this event will be fired as soon as the image is loaded
         image.onload = function(e) {
@@ -345,7 +345,7 @@ Discourse.Utilities = {
           // draw the image into the canvas
           canvas.getContext("2d").drawImage(img, x, y, dimension, dimension, 0, 0, size, size);
           // retrieve the image from the canvas
-          promise.resolve(canvas.toDataURL(fileType));
+          resolve(canvas.toDataURL(fileType));
         };
         // launch the onload event
         image.src = url;

app/assets/javascripts/discourse/mixins/ajax.js

@@ -40,10 +40,10 @@ Discourse.Ajax = Em.Mixin.create({
       Ember.Logger.error("DEPRECATION: Discourse.ajax should use promises, received 'error' callback");
     }
 
-    var performAjax = function(promise) {
+    var performAjax = function(resolve, reject) {
       var oldSuccess = args.success;
       args.success = function(xhr) {
-        Ember.run(promise, promise.resolve, xhr);
+        Ember.run(null, resolve, xhr);
         if (oldSuccess) oldSuccess(xhr);
       };
 
@@ -63,7 +63,7 @@ Discourse.Ajax = Em.Mixin.create({
         xhr.jqTextStatus = textStatus;
         xhr.requestedUrl = url;
 
-        Ember.run(promise, promise.reject, xhr);
+        Ember.run(null, reject, xhr);
         if (oldError) oldError(xhr);
       };
 
@@ -82,15 +82,15 @@ Discourse.Ajax = Em.Mixin.create({
     // For cached pages we strip out CSRF tokens, need to round trip to server prior to sending the
     //  request (bypass for GET, not needed)
     if(args.type && args.type.toUpperCase() !== 'GET' && !Discourse.Session.currentProp('csrfToken')){
-      return Ember.Deferred.promise(function(promise){
+      return new Ember.RSVP.Promise(function(resolve, reject){
         $.ajax(Discourse.getURL('/session/csrf'), {cache: false})
            .success(function(result){
               Discourse.Session.currentProp('csrfToken', result.csrf);
-              performAjax(promise);
+              performAjax(resolve, reject);
            });
       });
     } else {
-      return Ember.Deferred.promise(performAjax);
+      return new Ember.RSVP.Promise(performAjax);
     }
   }