Revised version of Android UI component operator
Drop use of WeakReferences and use a custom subscription instead
update TODOs according to meeting
Drop volatile in favor of failing fast if not subscribed from UI thread
Only release references in unsubscribe

We decided it's better to leave it to the caller when it's appropriate to release, cf. #1
Add guards around log statements
Remove isFinishing check when calling back to activities

We decided it's sufficient for the callback to be safe as long as the caller unsubscribes in onDestroy
Implemented the 'TimeInterval' operator
Implemented the scheduler version of the 'Return' operator
Updated the comments
Fixed issue #417
Merge branch 'master' of github.com:Netflix/RxJava into scalaadaptor
add one TODO
Fixed testOnErrorViaHasNext in issue #383
Removed the unnecessary 'catch' and 'fail'
Blocked 'hasNext' instead of 'next' until any notification arrives
Followed the iterator contract
Force 'hasNext' and 'next' throw the error once they have already thrown it before
some documentation for CompletenessTest
Fixed issue #454