Allow user registration open/close from user settings.json ?

[ghost]

As having a user account is apparently currently sufficient to be allowed upload a package, since django-registration is integrated, it may be useful to be able to block new user registration facility on a temporary or permanent basis. Of course, perhaps you don't want to complicate the exposed user settings, but I guess just something like the following in settings.py might do it.

REGISTRATION_OPEN = USER_SETTINGS['USER_REGISTRATION_OPEN'] 

(cosmetically, it might be worth also hiding the user registration link if user registration is thusly closed)