Add an option to enable or disable the "Build triggered." message sent
by Jenkins to the GitLab merge request.
Place "Build finished." portion of message in the user-configured
message and on the same line.  This will allow the user to start the
message with +1/-1, making use of GitLab's +1/-1 detection in merge
request comments.
Merge pull request #12 from mjdetullio/feature/optional-build-triggered-comment

Optional build triggered comment, make "Build finished" portion of comment user-configurable