Always add Google and Android repositories

Fix #23 
With version 0.10.0 of the Android Gradle plugin, the support libraries and the Play library were always marked as outdated, triggering the downloads at each build.

Turns out the Android Gradle plugin is not including the M2 repositories anymore, and the dependencies cannot be resolved.

Previously, we were adding the repos only if they were physically missing. This PR always adds the repositories anyway (unless no dependency).

Waiting for feedback!