feat(ngResource): Add $abort method to objects returned by $resource "class" actions

`$resource` "class" actions delegate to `$http` in a fashion that does not allow to pass timeout promise to individual requests. Hence these individual requests can not be cancelled. This patch adds $abort method to the object returned by `$resource` "class" actions.

Closes angular#5612

Author: Artemy Tregubenko

src/ngResource/resource.js

@@ -506,8 +506,9 @@ angular.module('ngResource', ['ng']).
           // If parameters do not contain `timeout` which is a promise, create it,
           // so that later this call can be aborted by resolving this promise
           var timeout = httpConfig.timeout;
+          var timeoutDeferred;
           if (!timeout || !timeout.then) {
-            var timeoutDeferred = $q.defer();
+            timeoutDeferred = $q.defer();
             httpConfig.timeout = timeoutDeferred.promise;
             // If timeout is specified in milliseconds, use it to abort via promise
             if (timeout) $timeout(timeoutDeferred.resolve, timeout);