Add -[RACCompoundDisposable removeDisposable:]
Allow nil in -removeDisposable:

This way, you can keep a disposable in a weak reference and not worry
about checking it before passing it in.
Remove recursive scheduling disposables when they're done
Remove -bind: disposables when done
Remove subscribeForever() disposables when done
Use compound disposables to avoid races and add some AR pools
Don't weakly capture the top-level compound disposable

This will prevent the sub-disposables from getting disposed properly
Wrap removing weak disposables in an autorelease pool
Merge pull request #274 from github/bounded-compound-disposables

Remove -bind:, subscribeForever(), and -scheduleRecursiveBlock: disposables when done