Upgrade to RxJava 0.17.1 + cgeo patch

There is an ongoing problem with RxJava, discussed at
https://github.com/Netflix/RxJava/issues/979

This version includes a patch available at
https://github.com/cgeo/RxJava/commit/9ffb27f310d9f454d10d4d03206d8b5a262f6d63

fixup! Upgrade to RxJava 0.17.1
Better handling of unsubscriptions
Use existing variable