Deploy snapshots to from master travis build

You would need to update attached .travis.yml with your sonatype username and encrypted password (I see you've posted some snapshots in the past).  For encrypting, see http://docs.travis-ci.com/user/environment-variables/#Secure-Variables.  I've done similar here: https://github.com/glowroot/glowroot/blob/master/.travis.yml.

I need to consume the latest immutables jars in my own travis build, so if you can deploy snapshot, I can just point to that until you are ready for next maven central release.  Thanks.