fix `_parseObject()` that got broken because of angular/angular.js#6253

The behavior of `angular.toJson()` has changed in Angular.js 1.3.0.beta-11, and it no longer strips properties starting with `$`. This breaks `$bind()`, since it tries to sync the `$id` property of objects back to server and fails. 

Fixed by manually stripping everything that starts with a `$` in `_parseObject()`.