Team/registration improvements

[andrasbacsai]

1. Admin users (root team) should see all teams created by all users and be able to delete them.
2. Admin users (root team) should be able to see all registered users and be able to delete them.
3. Registered users should be able to delete the teams they create.
4. Have the ability to create users manually from the Admin users (root team) if registration is off (or even if it's on).
5. Able to create account without password from the Admin users (root team) and on the first login the user should set the password
6. Able to send link invitations.