Fix for r85005: the getUserPermissionsErrors() calls were each returning a badaccess...

Fix for r85005: the getUserPermissionsErrors() calls were each returning a badaccess error when the user didn't have their particular permission, even if they had the other one, exclude these errors since they're already covered by the $user->isAllowedAny() check above.  Also fix processForm() to check isAllowed('import') for transwiki; this wasn't being done which meant users with importupload but not import (an unlikely combination to be fair) could still spoof the form.