added group model with most essential fields
added unit tests for crud ops on groups schema
simplified groups schema
added index on user field of groups schema
fixed syntax bugs
temporarily omitted test: remove group
Merge branch 'staging' of https://github.com/Fittr/fittr

Conflicts:
	app/coffee/test/users_spec.coffee
Merge pull request #151 from pieteradejong/master

added group model with basic crud tests