Implement omit for module args, also add tests for it

lib/ansible/utils/__init__.py

@@ -787,6 +787,10 @@ def _validate_both_dicts(a, b):
             "failed to combine variables, expected dicts but got a '%s' and a '%s'" % (type(a).__name__, type(b).__name__)
         )
 
+def serialize_args(args):
+    ''' convert a dict to a string of key/value items '''
+    return ' '.join("%s='%s'" % item for item in args.iteritems())
+
 def merge_hash(a, b):
     ''' recursively merges hash b into a
     keys from b take precedence over keys from a '''