feat($resource): add support for cancelling requests

Introduced changes:

- Deprecate passing a promise as `timeout` (for `$resource` actions).
  It never worked correctly anyway.
  Now a warning is logged (using `$log.debug()`) and the property is
  removed.
- Provide a `cancelRequest` static method on the Resource that will abort
  the request (if it's not already completed or aborted).
  If there is a numeric `timeout` specified on the action's configuration,
  this method will have no effect.

Example usage:

```js
var Post = $resource('/posts/:id', {id: '@id'}, {
  get: {
    method: 'GET'
  }
});

var currentPost = Post.get({id: 1});
...
// A moment later the user selects another post, so
// we don't need the previous request any more
Post.cancelRequest(currentPost);
currentPost = Post.get({id: 2});
...
```

BREAKING CHANGE:

Using a promise as `timeout` is no longer supported and will log a
warning. It never worked the way it was supposed to anyway.

Before:

```js
var deferred = $q.defer();
var User = $resource('/api/user/:id', {id: '@id'}, {
  get: {method: 'GET', timeout: deferred.promise}
});

var user = User.get({id: 1});   // sends a request
deferred.resolve();             // aborts the request

// Now, we need to re-define `User` passing a new promise as `timeout`
// or else all subsequent requests from `someAction` will be aborted
User = $resource(...);
user = User.get({id: 2});
```

After:

```js
var User = $resource('/api/user/:id', {id: '@id'}, {
  get: {method: 'GET'}
});

var user = User.get({id: 1});   // sends a request
User.cancelRequest(instance);   // aborts the request

user = User.get({id: 2});
```

Fixes angular#9332
Closes angular#13050
Closes angular#13058

src/ngResource/resource.js

@@ -365,7 +365,7 @@ angular.module('ngResource', ['ng']).
       }
     };
 
-    this.$get = ['$http', '$log', '$q', function($http, $log, $q) {
+    this.$get = ['$http', '$log', '$q', '$$HashMap', function($http, $log, $q, HashMap) {
 
       var noop = angular.noop,
         forEach = angular.forEach,
@@ -493,6 +493,7 @@ angular.module('ngResource', ['ng']).
 
       function resourceFactory(url, paramDefaults, actions, options) {
         var route = new Route(url, options);
+        var qTimeouts = new HashMap();
 
         actions = extend({}, provider.defaults.actions, actions);
 
@@ -515,6 +516,14 @@ angular.module('ngResource', ['ng']).
           shallowClearAndCopy(value || {}, this);
         }
 
+        Resource.cancelRequest = function(value) {
+          var qTimeout = qTimeouts.get(value);
+          if (qTimeout) {
+            qTimeout.resolve();
+            qTimeouts.remove(value);
+          }
+        };
+
         Resource.prototype.toJSON = function() {
           var data = extend({}, this);
           delete data.$promise;
@@ -535,14 +544,9 @@ angular.module('ngResource', ['ng']).
             delete action.timeout;
             hasTimeout = false;
           }
-          action.cancellable = hasTimeout ?
-              false : action.hasOwnProperty('cancellable') ?
-              action.cancellable : (options && options.hasOwnProperty('cancellable')) ?
-              options.cancellable :
-              provider.defaults.cancellable;
 
           Resource[name] = function(a1, a2, a3, a4) {
-            var params = {}, data, success, error;
+            var params = {}, data, success, error, qTimeout;
 
             /* jshint -W086 */ /* (purposefully fall through case statements) */
             switch (arguments.length) {
@@ -597,35 +601,28 @@ angular.module('ngResource', ['ng']).
                 case 'params':
                 case 'isArray':
                 case 'interceptor':
-                case 'cancellable':
                   break;
                 case 'timeout':
                   httpConfig[key] = value;
                   break;
               }
             });
 
-            if (!isInstanceCall) {
-              if (!action.cancellable) {
-                value.$cancelRequest = angular.noop;
-              } else {
-                var deferred = $q.defer();
-                httpConfig.timeout = deferred.promise;
-                value.$cancelRequest = deferred.resolve.bind(deferred);
-              }
-            }
-
             if (hasBody) httpConfig.data = data;
             route.setUrlParams(httpConfig,
               extend({}, extractParams(data, action.params || {}), params),
               action.url);
 
-            var promise = $http(httpConfig).finally(function() {
-              if (value.$cancelRequest) value.$cancelRequest = angular.noop;
-            }).then(function(response) {
+            if (!isInstanceCall && !httpConfig.timeout) {
+              qTimeout = $q.defer();
+              httpConfig.timeout = qTimeout.promise;
+              qTimeouts.put(value, qTimeout);
+            }
+
+            var promise = $http(httpConfig).then(function(response) {
+
               var data = response.data,
-                promise = value.$promise,
-                cancelRequest = value.$cancelRequest;
+                promise = value.$promise;
 
               if (data) {
                 // Need to convert action.isArray to boolean in case it is undefined
@@ -655,7 +652,6 @@ angular.module('ngResource', ['ng']).
                 }
               }
 
-              value.$cancelRequest = cancelRequest;
               value.$resolved = true;
 
               response.resource = value;
@@ -669,6 +665,13 @@ angular.module('ngResource', ['ng']).
               return $q.reject(response);
             });
 
+            // The request has completed (either successfully or in error)
+            // Make sure that we cancel the timeout if there was one
+            promise.finally(function() {
+              if (qTimeout) qTimeout.reject();
+              qTimeouts.remove(value);
+            });
+
             promise = promise.then(
               function(response) {
                 var value = responseInterceptor(response);