change the way sshd is configured

* use lineinfile for all things we care about
* disable root login via ssh
  * search for any existing PermitRootLogin instances
  * if found, replace with 'PermitRootLogin no', if not add
    'PermitRootLogin no' at the end of the file
* disable password authentication
* make sshd listen to public ip only
* enable sftp subsystem
Merge pull request #20 from sa2ajj/no-root-login

disable root login via SSH
fix task name
add vm1 to the list of hosts
actually use the ssh control session
Merge pull request #22 from djmitche/add-vm1

Add vm1
add nine.buildbot.net to buildbot.net zone

* also remove nine.buildbot.buildbot.net
* remove TXT record for nine.buildbot.net
Merge pull request #23 from sa2ajj/add-nine-to-dns

add nine.buildbot.net to buildbot.net zone
do not highlight group_by step