Added JAVA generator

This PR adds the JAVA MAVLink generator originally written for [DroidPlanner](https://github.com/DroidPlanner/droidplanner).

The changes from #228 are changing the name of the commit-er, and adding Java to the travis-ci build.
How do I get the string that corresponds to the dialect?

Also these line needs to be changed as well
https://github.com/mavlink/mavlink/pull/246/files#diff-55f26fca818dba1a47a156dcd1f0b90aR260