pyrocufflink-dhcp: DHCP reservations for VM hosts

When there is a network issue that prevents DNS names from being
resolved, it can be difficult to troubleshoot.  For example, last night,
the Samba domain controller crashed, so *pyrocufflink.blue* names were
unavailable.  Furthermore, the domain controller VM was apparently
locked up, so I could not SSH into it directly, and it needed to be
rebooted.  Since the VM host's name did not resolve, I could not find
its address to log into it and reboot the VM.  I resorted to scanning
the SSH keys of every IP address on the network until I found the one
that matched the cached key in ~/.ssh/known_hosts.  This was cumbersome
and annoying.

Assigning DHCP reservations to the VM hosts will ensure that when a
situation like this arises again, I can quickly connect to the correct
VM host and manage its virtual machines, as its address is recorded in
the configuration policy.

group_vars/pyrocufflink-dhcp.yml

@@ -84,6 +84,12 @@ dhcp_reservations:
 - host: logs0.pyrocufflink.blue
   ip_addr: 172.30.0.17
   mac_addr: 52:54:00:b1:84:98
+- host: vmhost0.pyrocufflink.blue
+  ip_addr: 172.30.0.18
+  mac_addr: e0:d5:5e:a2:2e:1a
+- host: vmhost1.pyrocufflink.blue
+  ip_addr: 172.30.0.19
+  mac_addr: e0:d5:5e:6e:ad:ac
 
 # Management
 - host: unifi0