title: Trigger Jenkins build every 2 hours but only if there was a git commit
body: <p>Here is the problem that I am having - I need to trigger a job build every 2  hours but only if there was a git commit(skip if there was no activity). 
  I can solve them individually but not sure how to solve them together - anybody has any good ideas?
  The only one I can come up with is a cron job that would check every 2 hours and if there is a git commit during that time, trigger a job manually, but that does not look all that elegant. </p>
  
  <p>Any good ideas appreciated.</p>