Add download-cached service

resources/assets/scripts/app/services/download-cached.coffee

@@ -0,0 +1,20 @@
+angular.module('ponyfm').factory('download-cached', [
+  '$rootScope', '$http', '$log'
+  ($rootScope, $http, $log) ->
+    download = (type, id, format) ->
+      url = '/api/web/' + type + '/download-cached/' + id + '/' + format
+
+      encodingComplete = (response) ->
+        if response.data.url == null
+          'pending'
+        else
+          response.data.url
+
+      encodingFailed = (error) ->
+        $log.error 'Error downloading encoded file - Status: ' + error.status + '- Message: ' + error.data
+        'error'
+
+      $http.get(url).then(encodingComplete).catch encodingFailed
+
+    {download: download}
+])