Add Reminder Severity type to notications

Reminders aren't warnings per se or suggestions.
Merge branch 'master' of github.com:ProjPossibility/2014-CSUN-CareTaker-1
Merge branch 'master' of github.com:ProjPossibility/2014-CSUN-CareTaker-1
Add the severity as a foreign key to notifications, update migrations and seeders.

severity now acts as a FK  in the database and seeder fixed.
Merge branch 'master' of github.com:ProjPossibility/2014-CSUN-CareTaker-1
Merge branch 'master' of github.com:ProjPossibility/2014-CSUN-CareTaker-1
Add appointment date time to the database.
Merge branch 'master' of github.com:ProjPossibility/2014-CSUN-CareTaker-1