added verbose option to show callback loaded info

also made mail module print nicer without all those 'u'

lib/ansible/plugins/callback/context_demo.py

@@ -24,6 +24,7 @@ class CallbackModule(CallbackBase):
     """
     CALLBACK_VERSION = 2.0
     CALLBACK_TYPE = 'aggregate'
+    CALLBACK_TYPE = 'context_demo'
 
     def v2_on_any(self, *args, **kwargs):
         i = 0