Very bad hack to start on basic authentication

I've a few private feeds I want my instance of commafeed to have access
to.  This is a pretty nasty hack to add support for basic authentication
-- but now that it's working (a little!) I can clean it up.

Things that would be nice to add:

 * translations!
 * storing the auth details in subscriptions, not feeds
 * storing the details in some form of 2-way crypt
 * making it more pluggable -- oauth type stuff?
 * making the auth details available in the feed settings area