Merge pull request #4 from RomanIakovlev/master

Updated to newer versions of Google Play Services and RxJava.
Modified sample app to use AndroidObservable.bindActivity instead of AndroidObservable.fromActivity, which is deprecated in RxJava 0.17. Removed explicit instruction to observe on main thread, because AndroidObservable.bindActivity already does that.
Replaced Subscriptions.create with AndroidSubscription.unsubscribeInUiThread in BaseLocationObservable.