* Show badge on group actor in WebUI

* Do not notify in case of  by following group actor

* If you mention group actor, also mention group actor followers

* Relax characters that can be used in username (same as Application)

* Revert "Relax characters that can be used in username (same as Application)"

This reverts commit 7e10a137b878d0db1b5252c52106faef5e09ca4b.

* Delete display_name method