Fix faulty pause/resume logic in PausableObservable and PausableBufferedObservable
Allow observable in addition to subject to be used as pauser
Document PausableObservable.resume/pause and PausableBufferedObservable.resume/pause
Merge pull request #256 from urmastalimaa/allow_observable_to_be_used_as_pauser

Allow any observable to be used as a controller to `pausable` and `pausableBuffered`