Subject based event bus (rxandroid-eventbus)

This is a long standing thing I meant to pull out of our app which has proven invaluable for us. It's just a thin wrapper around Rx subjects, but with an API that lends itself well for dependency injection.

Sample activity:
https://github.com/ReactiveX/RxAndroid/pull/60/files#diff-18

Sample service:
https://github.com/ReactiveX/RxAndroid/pull/60/files#diff-19
I pulled and looked at the code and I agree with Jake. The currently exposed API isn't very reactive. It feels like it implements a "standard" event bus using RxJava rather than implementing a reactive event bus.

Exposing an Observable and adding convenience operators for filtering/etc.. would be much nicer and fit with in more nicely with everything else.

What that would look like I have no idea.