Publish operator on Observable

https://github.com/Netflix/RxJava/issues/15
Replay operator on Observable

https://github.com/Netflix/RxJava/issues/71
Cache operator

Cache operator as discussed in https://github.com/Netflix/RxJava/pull/209

Similar to `replay()` except that this auto-subscribes to the source sequence. This comes with the same cautions as `toList` when dealing with infinite or very large sequences.
Re-order count increment to make unit tests deterministic
remove debug statements from unit tests
Merge pull request #263 from benjchristensen/publish-replay-cache

Publish, Replay and Cache Operators