Build java client on travis

I think we should introduce travis build as part of the PR build process for our java. I already have travis configuration for node, but I would like to know your guys opinion before adding this to the repos.

WDYT? mwessend@redhat.com lrossett aliok@redhat.com luigizuccarelli_jira

mwessend@redhat.com - let's use this ticket to gather general requirements and opinions. We can provide more details later.