Show friends or peers or search in users directory

Pick the first that actually contain users.
fix user.peers.any? and user.peers.count

The construct_scope did not affect counting
show my groups by default in groups dir

If I'm not in any groups show the group search instead.
Merge pull request #119 from azul/feature/default-to-friends-dir

Feature/default to friends dir
first take on a search based user directory
refactor: UserFinder to search for users

also changed the default to friends
fix search and remove order by login

Order by login was making the queries crazy slow
remove autoredirect on single user search, enable history

using the History extension for backward compatibility
This way previous and next page navigation can be used with ajax