Update README.md
Rename license.txt to LICENSE.txt
Update README.md
Add ability to edit users from admin panel.
Add "accepted" status to group requests.

Refactor group_requests invitations system
Add "Mark as spam" option to group_requests admin page
Merge branch 'feature/improve-admin' of github.com:loomio/loomio into feature/improve-admin

* 'feature/improve-admin' of github.com:loomio/loomio:
  The first part of updating the invitation process Add specs for start_new_group