Permissions

A region has a set of admins, and that set are allowed to set permissions on pages, maps, etc.

We shouldn't use the Django admin for this because it's too leaky -- there's far too much extra detail everywhere.

• Done. Set permissions on pages/maps/etc for a given user.
• Wont fix: Create groups of users, and set permissions based on those groups.
  • It seems like this per-group permission stuff isn't really used, even in Davis.  Probably best to axe it to keep the implementation simple here.  We can always create something like this later if needed.
• Done. Ban users.  Need something different from the current Banned group, which acts globally.
• Done. Add / remove admins.
• Done. Set region-wide settings
  • Default region language
• Done. Cover photo should use an is_region_admin check.

Possible implementation

We want to keep global permissions / adminship for things like blocking spammers, horribly evil people, etc.  "Admins" here would be LocalWiki volunteers rather than per-LocalWiki admins, and wouldn't e.g. set content policy.