General cleanup of the groups REST API. Moved logic to internalAPI. Some reuse of logic. Does not work yet, though...
Added error handling in the data adapters.
Minor cleanup and typo fixes.
groups-test now runs again, tests only minimal stuff.
"@softwerkskammer.de" suffix should be added where it is required - at the lowest possible level.
Moved group filtering to where it belongs.
Merge remote-tracking branch 'upstream/master'

Conflicts:
	lib/groups/index.js
	lib/groups/internalAPI.js
Oops, fixed remains of refactoring.
Forgot to add an err parameter to an async.waterfall callback.
Cleanup of some comments.
Added nicer titles to the groups pages.
Merge pull request #41 from NicoleRauch/master

Cleaned up the REST API of the groups module.