Run ansible in a crontask on service hosts

Because this won't work well in development (it will always look at
prod-hosts), it's easily disabled with no_ansible_pull=true in the
inventory.  Fixes #3089.
use a git:// URL
Focus on local.yml for all Ansible runs
configure service hosts too, and move ansible-pull tasks to 'base'
install ansible repo in service account's home
mention ansible runs non-priviledged
Fix bootstrapping to work with local.yml.
use an explicit branch
fix README typo
Merge djmitche/buildbot-infra:pull-cron (PR #37)
set up vm1 as a servicehost, too
Merge pull request #41 from djmitche/add-vm1

set up vm1 as a servicehost, too
bump buildbot.net zone serial number

* so we can actually deploy it
apply base role to ns1

* another option is to make 'dns' role depend on 'base'
fix the dns role

* no localhost -> introduce internal_ip and use it for rndc
  communication
* create the rndc config file (since we use a non-standard address)
* create the rndc key in a non-default location (prevents annoying
  warnings)
Merge pull request #42 from sa2ajj/dns-serial-bump

bump buildbot.net zone serial number
use the item value not key
Merge pull request #43 from sa2ajj/fix-bb-master

use the item value not key
re-order buildbot.net zone items

* this allows to easily see what services are run flosoft server
* no other changes -> no serial bump
Merge pull request #44 from sa2ajj/reorder-zone-items

re-order buildbot.net zone items