TryGhost/Ghost — pull request #4547 by jaswilli (2014-11-29 20:13:23+00:00)
Title: Prevent silent failures and recover after error.

Refs #4543
- Alway return model out of save handler so sub-classes which
call this._super() on save have a model on success and failure.
- Always return resolved promise out of post slug generator.
- Test the errors object in the error notification helper to avoid
throwing an unhandled exception and silently failing.