feat($resource): deep-merge custom actions with default actions.

Previously, if you wanted to specify a timeout, transform, interceptor, or any
other property for an action, you also had to include the other properties of
the default action (method, isArray):

```
var Resource = $resource('/foo', {}, { save: { method: 'POST', timeout: 10000 }});
```

Now, a deep-merge between the provided custom actions and the default actions
will be performed, so you can specify just the properties you want to add or
override:

```
var Resource = $resource('/foo', {}, { save: { timeout: 10000 }});
```

Author: gabrielmaldi

src/ngResource/resource.js

@@ -516,6 +516,7 @@ angular.module('ngResource', ['ng']).
       var noop = angular.noop,
         forEach = angular.forEach,
         extend = angular.extend,
+        merge = angular.merge,
         copy = angular.copy,
         isFunction = angular.isFunction;
 
@@ -640,7 +641,7 @@ angular.module('ngResource', ['ng']).
       function resourceFactory(url, paramDefaults, actions, options) {
         var route = new Route(url, options);
 
-        actions = extend({}, provider.defaults.actions, actions);
+        actions = merge({}, provider.defaults.actions, actions);
 
         function extractParams(data, actionParams) {
           var ids = {};

test/ngResource/resourceSpec.js

@@ -487,6 +487,19 @@ describe("basic usage", function() {
   });
 
 
+  it('should deep-merge custom actions with default actions', function() {
+    $httpBackend.when('GET', '/foo').respond({invokedMethod: 'get'});
+    $httpBackend.when('POST', '/foo').respond({invokedMethod: 'post'});
+
+    var Resource = $resource('/foo', {}, {save: {timeout: 10000}});
+    var resource = new Resource();
+    var response = Resource.save();
+
+    $httpBackend.flush();
+    expect(response.invokedMethod).toEqual('post');
+  });
+
+
   it("should read partial resource", function() {
     $httpBackend.expect('GET', '/CreditCard').respond([{id:{key:123}}]);
     var ccs = CreditCard.query();