* Only repo owner or person who shared this repo can view repo page.
* Remove group user even when user is deleted by admin.
* Paginator link on admin page.
* when ACTIVATE_AFTER_REGISTRATION set to True, user will be activated after registration, and no email sending;
* when ACTIVATE_AFTER_REGISTRATION set to False, and REGISTRAION_SEND_EMAIL set to True, user will be activated by email;
* when ACTIVATE_AFTER_REGISTRATION set to False, and REGISTRAION_SEND_EMAIL set to Flase, user will be activated by admin.