in commit 0e28281a the code for thumbnailing got refactored and the
renaming of this variables was not done correctly.

Signed-Off-by: Matthias Kesler <krombel@krombel.de>

 Implement GET /groups/$groupId/invited_users

Log a warning when no profile for invited member

And return empty profile

Omit the *s for @room notifications

They're just redundant

 Basic implementation of backup media store