Support proper login to the UI

This feature was requested at the NetarchiveSuite workshop in September 2007:
Having the UI know of its user would be helpful in several ways. It would allow limited access to specific users (e.g. history only or add seeds only). It would allow for knowing who did what (see also requests #1137 and #1119). It could also allow for some personalization say having quick access to items that you've been working on recently.
Surely there's some kind of pluggable architecture available so we can just hook up to LDAP/Active Directory/whatever.