Minor fixes to $firebaseAuth

[jwngr]

@katowulf - A few small fixes for $firebaseAuth

[katowulf]

I wonder if we should be doing any internal error handling here, perhaps triggering events in the Angular scope. Hrm. Something to think about.

[jwngr]

Their callback will already receive the errors and they can do what they want with them.

[katowulf]

Callbacks aren't terribly convenient in all architectures. An event broadcasting strategy can be pretty handy for things like this. It's not impossible or particularly hard to add a .run() method that implements this, if one is versed in Angular and AngularFire, but it's worth pondering as part of the API as lots of people utilize $emit and $broadcast as a basic pattern (particularly when talking to directives)

[jwngr]

Gotcha, add it to our discussion list for the meeting this week. Sounds like a reasonable idea.

[jamestalmage]

See #474 for an alternative idea.