Set default time zone value for Profile default TIME_ZONE settings

I don't quite understand why the default value of the timezone field in the models.Profile class is an empty string, when the TIME_ZONE value in the Django settings would make a perfect default value imho. This is why I changed it so timezone in models.Profile by default uses whatever is in settings.TIME_ZONE because it made sense in my deployment where it was the easiest way to set a sensible default timezone value for profiles that were automatically created via allauth. It should be safe to do it like this as TIME_ZONE is always set in the default mailman Django settings.py as far as I know.