Mavenized/Gradle'ized so we can push snapshots and releases.

* Depends on LibGDX 1.2.0
* Task gradlew publishMavenJavaPublicationToMavenRepository Im not even kidding <


This requires the login credentials for sonatype and central, which can be put in a local gradle.properties on the build server. (I've assumed they could be different, hence sonatypeUser : releaseUser)