Added Group document.
Moved group to groups. Added blueprint and testing.

The testing currently fails locally for me, if someone could take a look at it for me it would be appreciated :)
Small amounts of cleanup.
Fixed it myself *dance*
GET groups/ works. Completes part 1 of #48
More testing.
POST /groups now works. Part 2 of #48 complete.
GET /groups/<name> works. Completes part 3 of #48
PUT /groups/<id> works. Completes part 4 of #48
DELETE /groups/<id> now works. Completes part 5 of #48
Merge branch 'feature/48-groups' into develop. Closes #48