Add hasObservers to Subject

[yogurtearl]

Other implementations of Rx have a hasObservers method on Subject. It would be nice to have this in RxJava.

RxJS:
https://github.com/Reactive-Extensions/RxJS/blob/master/doc/api/subjects/subject.md#rxsubjectprototypehasobservers

Rx.NET
https://rx.codeplex.com/SourceControl/latest#Rx.NET/Source/System.Reactive.Linq/Reactive/Subjects/Subject.cs

[benjchristensen]

I'm open to that. Want to submit a pull request?

[simonbasle]

went ahead and implemented the method (see pull request)

[benjchristensen]

Merged.