Fix Interest List

Fixes the interest list

• The interest list is now displayed on both the project and the group page to avoid confusion/users missing it (#102 (closed))
• The interest list sends a notification whenever there are enough users to form a group (#48 (closed))
• The interest list sends a notification whenever a group switches to looking for members
• Removed the explanation that groups can invite users from the interest list since this is not true, and created an issue for it (#138 (closed)).
• Fix menu inconsistency where going to the group dashboard page is only possible from the overview.

Other changes:

• Sort notification preferences
• Improve some of the notification messages

Closes #102 (closed)
Closes #48 (closed)