users can not be friends of them self
friends in creation script
removed obsolete methods
refactored DAO's
group members are saved in users instead of groups
use UserReference for group and friend methods
link to base group URI in group listings
link to base user URI in friend listings
Merge branch 'dev'

* dev:
  link to base user URI in friend listings
  link to base group URI in group listings
  use UserReference for group and friend methods
  group members are saved in users instead of groups
  refactored DAO's
  removed obsolete methods
  friends in creation script
  users can not be friends of them self