some updates to the host retirement procedure

= Decommissioning a host =

* stop the VM: virsh destroy $host

* undefine it: virsh undefine $host

* remove the LVM logical volumes

* remove it from the tor-virt git

* remove it from ud-ldap

* on pauli:

** puppetca revoke $host.torproject.org

** puppetca clean $host.torproject.org

** puppet node clean $host.torproject.org

* if applicable, stop the VM: virsh destroy $host

* if applicable, undefine it: virsh undefine $host

* if applicable, remove the LVM logical volumes or virtual disk files

* remove it from ud-ldap: the host entry and any @<host> group memberships there might be as well as any sudo passwords users might have configured for that host

* if it has any associated records in tor-dns/domains or auto-dns, remove it from there too

* on pauli:   read x ; puppet node clean $x.torproject.org && puppet node deactivate $x.torproject.org

* grep the tor-puppet repo for the host (and maybe its IP addresses) and clean up