Merge pull request #35 from opentok/develop

Release 2.3.0
Merge branch 'develop' of https://github.com/opentok/OpenTokRTC-Android into add_gradle_support
Adding gradle support
Updating versionCode and versionName
Updating versionsCode and versionName from gradle
Merge pull request #39 from marinaserranomontes/add_gradle_support

Add gradle support