make callbacks declare needing whitelisting

this will allow for custom or v1 callbacks locally loaded to automatically be triggered as they were in 1.x

lib/ansible/plugins/callback/profile_tasks.py

@@ -69,6 +69,7 @@ class CallbackModule(CallbackBase):
     CALLBACK_VERSION = 2.0
     CALLBACK_TYPE = 'aggregate'
     CALLBACK_NAME = 'profile_tasks'
+    CALLBACK_NEEDS_WHITELIST = True
 
     def __init__(self, display):
         self.stats = {}