Initial commit of the Android samples module

refs https://github.com/soundcloud/RxJava/issues/3
Simplify version property forwarding
Fix project import issue in Android Studio and a compilation failure
Bump Android plugin version to 0.9
Switch to customizable Gradle wrapper
Trigger samples build manually via Gradle build property
Merge remote-tracking branch 'netflix/master' into android-samples
Revert to using the all Gradle wrapper dist type
Add full example for Activity + retained fragment + cache
Add sample for fragments and connectable observables
Add sample for binding to list adapters in ListFragment
Merge pull request #930 from mttkay/android-samples

Initial commit of the Android samples module