Modified gradle build so it pushes an 'aar' file to Maven instead of an ...

If you could please push a signed AAR repository to MavenCentral I would be much obliged.

Added maven_push.gradle, a script from Chris Banes (https://github.com/chrisbanes) for pushing to Sonatype repository. Modified so it pushes to file://localhost/local-repo instead.

Modified gradle build so it pushes an 'aar' file to Maven instead of an 'apklib'. 

Needed to support to aar because gradle build has problems with duplicate AndroidManifest.xml in apklibs for some reason.