Change controllers to array controllers

app/controllers/episodes.js

@@ -1,6 +1,6 @@
 import Ember from 'ember';
 
-export default Ember.Controller.extend({
+export default Ember.ArrayController.extend({
     needs: ['player'],
 
     sortAscending: false,

app/controllers/podcasts.js

@@ -1,5 +1,5 @@
 import Ember from 'ember';
 
-export default Ember.Controller.extend({
+export default Ember.ArrayController.extend({
   sortProperties: ['title']
 });