Start work on the core delete function.

Currently does:
* kills users
* takes a backup of their ldap entry to /home/deleted/$user/ldap-ldif
* deletes them from ldap
* moves their homedir to /home/deleted/$user/homedir
* moves their mbox to /home/deleted/$user/mbox
* deletes them from the printer credit db

Doesn't do:
* sends an email saying their account is/has been deleted
* unsubscribe from mailing lists
* delete from DB
* add entery to old members table
* anything else i've forgotten