Not forcing build with API 20 Preview (or 20 wearable), unless the API is stable
Fixed Gradle artefactId typo in README
Added Gradle Wrapper, version 1.12
Updated Travis CI configuration
Travis CI licenses
Travis CI licenses
Travis CI components/licenses update
Added callback methods hinting where appropriate
ConcurrentModificationException fixed, Closing #632
Not required lines for Travis, DUMB terminal by default