Being able to override url in resource actions

A pull request already existed (https://github.com/angular/angular.js/pull/1890)
but i found out that the url set up in the action would not have their params replaced.

This is what I intent to do here:
```javascript
      var TypeItem = $resource('', {type: 'Order'}, {
          get: {
              method: 'GET',
              params: {type: 'Customer'},
              url: '/:type/:typeId'
          }
      });
      var item = TypeItem.get({typeId: 123});
```
will call `/Customer/123`