Support alternate authentication models
We should allow rules for sites that are brave enough to refuse to pay the SSL mafia any protection money, yet are still authenticated by other authentication mechanisms, such as MonkeySphere or Perspectives.
Ideally, such rule sets or rule feeds would come with special attributes that designate which authentication mechanism they require, so that we can disable them unless either the user explicitly enables them, or if the appropriate 3rd party Firefox extension is detected and installed.
This attribute could either take the form of authenticated_by="perspectives,monkeysphere,manual", or it could take an individual keyword=value pair, to provide additional options to the authentication addon to determine if the rule should be automatically enabled. (Ie such as auth_monkeysphere="key_id=0xgpg_id").