Add ping method to auth engines to determine if they are reachable

data/users/__init__.py

@@ -150,6 +150,10 @@ class UserAuthentication(object):
 
     return data.get('password', encrypted)
 
+  def ping(self):
+    """ Returns whether the authentication engine is reachable and working. """
+    return self.state.ping()
+
   @property
   def federated_service(self):
     """ Returns the name of the federated service for the auth system. If none, should return None.