chore(auth): Auth fixes and method additions (angular#132)

* feat(list): Add methods to FirebaseListObservable

* feat(list): .remove() should remove the whole list if no param is provided

* chore(utils): Add utils for runtime type checking

* feat(list): Accept url or ref

* chore(utils): function for checking for url or firebase ref

* feat(object): Accept a ref for .object()

* fix(auth): login() with Password provides credentials

* fix(auth): Add expires to FirebaseAuthState

* fix(auth): Add PasswordCredentials interface

* feat(auth): Add createUser method on auth

* fix(auth): Add expires in original declaration

Author: davideast