External Users

The user has the rights of a public user execpt it can never create a project, group, or team. Also it cant view internal projects.

Partially fix for both #4009 and #13938 (except the LDAP sync or a pattern to detect external users)


![Screen_Shot_2016-03-14_at_22.02.52](/uploads/486a84ab3acb98c6cfb71a4ec7d268e2/Screen_Shot_2016-03-14_at_22.02.52.png)

See merge request !3171