Adding explicitly set ircbot notifications

Summary:
This adds a new configuration setting:

"notification.actions" : [
  "commit",
  "abandon",
  "actions"
]

if not set, displays all actions, if is set, display only what is set to display

Test Plan: add the notification.actions settings and set accordingly

Reviewers: epriestley, zeeg

CC: aran, epriestley

Differential Revision: https://secure.phabricator.com/D1820