Reviewer Mike - Faster chef client

This implements the changes I proposed last week to cut down on the amount of work chef-client does.  I've tested by:
 * running chef-client when there's nothing to do (now takes ~8 seconds, as opposed to 1:32 before this change)
 * adding a homestead to an existing cluster (so one homestead has very little to do and the other has to do a full install)