Add find() method to CrudManager

Add a find() methods to CrudManager to maintain compatability
with existing CLI lookups using utils.find_resource().

Change-Id: Ia9b38b975bb88fb361f3471b66f98c7e81bbc6de
attempt to add tests

Change-Id: I5915a2da7c296cb7ae773ba7682860570b8c20a8