Use cfg's new print_help() method

Change-Id: Ib8e5dc50bc9773d13b8d9c741676477aa0f001e0

keystone/config.py

@@ -32,9 +32,6 @@ class ConfigMixin(object):
         kw.setdefault('args', [])
         return super(ConfigMixin, self).__call__(*args, **kw)
 
-    def print_help(self):
-        self._oparser.print_help()
-
     def set_usage(self, usage):
         self.usage = usage
         self._oparser.usage = usage

keystone/openstack/common/cfg.py

@@ -962,6 +962,10 @@ class ConfigOpts(collections.Mapping):
         """Print the usage message for the current program."""
         self._oparser.print_usage(file)
 
+    def print_help(self, file=None):
+        """Print the help message for the current program."""
+        self._oparser.print_help(file)
+
     def _get(self, name, group=None):
         """Look up an option value.