Fix exception blowing up the webapp when a config option does not exist.
Update core.py
Notifications should use the right ObjectId.

Solves an issue with not being able to pivot off of the Notifications
list in a user profile.
Merge pull request #227 from frbapolkosnik/patch-2

Fix exception from blowing up the webapp when a config option does not exist.
Merge branch 'master' into distributed_services

Conflicts:
	crits/services/core.py