Setup Jenkins CI job for Puppet Server with JRuby 9k

We should setup a Jenkins CI pipeline which covers the standard OSS Puppet Server pipeline but with JRuby 9k being used instead of JRuby 1.7. The ability to do this will depend upon the initial support for this being completed in SERVER-1630 and SERVER-1772.

Test jobs run under JRuby 9k have so far been seen to be considerably slower (up to 2x slower for just the Clojure unit tests) than when running with JRuby 1.7. We'll probably want to setup the JRuby 9k pipeline to run disconnected from and less frequently than the standard mergely/nightly pipelines, which would continue to run with JRuby 1.7. It may be sufficient for now to just have a "weekly" JRuby 9k job, with the ability to manually trigger that job just before a release if needed. We should consult with some QA folks, e.g, John Duarte and Eric Thompson, for their opinions as to what the frequency of the job should be.