Use new synchronization helpers to avoid races when deploying with HA

There are a number of possible races when deploying nova for the
first time:

 - when creating of the database / database user
 - when registering the endpoint and creating users in keystone
 - setting availability zones for compute nodes
Manage nova-controller services with pacemaker

We create the primitives/group/clone resources (protected with
crowbar_pacemaker_sync_mark) and we use the
Chef::Provider::CrowbarPacemakerService service provider.
Merge pull request #341 from vuntz/sync-marks

Use new synchronization helpers + manage services with pacemaker
Run crowbar-nova-set-availability-zone command in a delayed notification

Until now, we were running the crowbar-nova-set-availability-zone calls
as part of the chef run, which resulted in a loss of nova-related
notification if the calls ever failed. This could result in services not
being restarted after a config change.

So instead, we use the same trick as in the neutron cookbook and we run
the commands in a delayed notification, so that it runs at the end.

This makes us lose the synchronization, but I don't think it's strictly
require here.

(Failures might still impact notifications of cookbooks coming later,
but that's less likely than in the nova case)