Explicitly list protocols that are allowed, rather than using their initials.  Also, add cid, which I need for my mailstream plugin to work.
The post_remote_end hook was being called with an escaped version of the item, not very useful.  This change moves the hook to the end of item_store and gets all data fresh from the database.
Merge pull request #648 from mexon/mailstream-prerequisites

Mailstream prerequisites