Add TravisCI integration with JRuby

Now that we support JRuby, ensure we run our tests in a JRuby
environment with Travis.

Change-Id: I27fea02ed5c9a42bb38a6f8654599f478ef12fb2
Reviewed-on: http://gerrit.causes.com/36000
Tested-by: jenkins <jenkins@causes.com>
Reviewed-by: Shane da Silva <shane@causes.com>