Make the CS ACCESS output friendlier

At Ashton's request, uses nicknames instead of account IDs in the output of ChanServ's ACCESS command when viewing a channel's access list.  This implementation assumes that the oldest nick currently registered to a user is that user's primary nickname.
I chose to use nicknames because sometimes display names aren't at all related to a user's nick, and nicknames are probably more recognizable for IRC.

This probably also supplements Fugiman's request as outlined in #184.
Also related to #184: There may be merge conflicts in one of either this or that if the other is merged.  If that occurs, let me know and I'll pull and rebase on the new master for the outstanding pull request.