Android42

This downgrades the minimal target SDK from 19 (4.4 kitkat) to 17 (4.2 jellybean). When building this yields a 4.2 and 4.4 `apk`, with improved 4.4 API calls used only when installed on 4.4 (basically it makes webmaker-app more responsive/performant on 4.4 while also running on 4.2)