feat($resource): support HTTP PATCH method

Properly serialize data into request body instead of url.

Closes #887

test/ngResource/resourceSpec.js

@@ -11,6 +11,9 @@ describe("resource", function() {
       charge:{
         method:'POST',
         params:{verb:'!charge'}
+      },
+      patch: {
+        method: 'PATCH'
       }
     });
     callback = jasmine.createSpy();
@@ -235,6 +238,20 @@ describe("resource", function() {
   });
 
 
+  it("should patch a resource", function() {
+    $httpBackend.expectPATCH('/CreditCard/123', '{"name":"igor"}').
+                     respond({id: 123, name: 'rama'});
+
+    var card = CreditCard.patch({id: 123}, {name: 'igor'}, callback);
+
+    expect(card).toEqualData({name: 'igor'});
+    expect(callback).not.toHaveBeenCalled();
+    $httpBackend.flush();
+    expect(callback).toHaveBeenCalled();
+    expect(card).toEqualData({id: 123, name: 'rama'});
+  });
+
+
   it('should create on save', function() {
     $httpBackend.expect('POST', '/CreditCard', '{"name":"misko"}').respond({id: 123}, {header1: 'a'});