Adding release notes.

Also updating the prep script for things that need to happen to go from
3.0 to 3.1 (which isn't a lot!).
Merge branch 'master' into release_notes
Release notes and README updates.
Fixing bug in prep script.

The prep script fixes an issue with running create_default_collections
on older databases which haven't had their indexes fixed.
Merge pull request #226 from crits/release_notes

Release notes
Merge branch 'master' into stable_3
Fix exception blowing up the webapp when a config option does not exist.
Change form label to DB version.
Merge branch 'master' of github.com:crits/crits
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 stable_3