Followup Idfee1b4d per Tim

Followup Idfee1b4d per Tim

OAuth was going to return different values for UserIsEveryoneAllowed
depending on whether OAuth headers were provided, so the bolding on
Special:SpecialPages wouldn't be odd. That wasn't liked, so instead
we'll only mark special pages as restricted based on $wgGroupPermissions
and not what extensions might do.

Also, it was suggested that if an extension can remove 'read' then the
cache headers set by RawAction and the API should reflect that.

Change-Id: I381553e79c5320083c6d6d9ddd5bc0b146600f9e