Populate module_setup from the setup module rather than special code elsewhere

This small change allows for individual setup actions to populate the SETUP_CACHE and not cause a subsequent facts-gathering when not needed. This follows the standard of other facts modules as laid out in #1206 and implemented in fedfd187. It allows to test of the setup module has already been run even when gather_facts was explicitely disabled.

lib/ansible/playbook/__init__.py

@@ -525,7 +525,6 @@ class PlayBook(object):
         # let runner template out future commands
         setup_ok = setup_results.get('contacted', {})
         for (host, result) in setup_ok.iteritems():
-            self.SETUP_CACHE[host].update({'module_setup': True})
             self.SETUP_CACHE[host].update(result.get('ansible_facts', {}))
         return setup_results