Split out haproxy recipe in crowbar-pacemaker

No code change, but we have a better split of the code.
Only load crm-initial.conf when the file got changed

There is no point in loading it if it's the same as before, since we
already imported these settings.
Make stonith-enabled/no-quorum-policy variables in crm-initial.conf

The values will change depending on options in the wrapper, or other
factors.
Add a STONITH recipe

By default, STONITH is marked as disabled. It can be enabled and
configured:

 - manually (by the user)
 - with a stonith plugin that will be used with a clone resource
 - with a stonith plugin that will have per-node parameters
Check that the specified STONITH plugin is available

We simply need to check if the plugin is in the output of "stonith -L".
Compute no-quorum-policy based on number of members in the cluster

This is "ignore" if we have 1 or 2 members, and "stop" (the default) for
more members.

We do this magic in the crowbar-pacemaker cookbook, since we have the
required information there.
Add support for IPMI as STONITH in crowbar-pacemaker

Since Crowbar can know about IPMI configuration of nodes, we can
translate this into a valid STONITH configuration.
Add support for using libvirt STONITH plugin in crowbar-pacemaker

For development purposes, it's very useful to be able to simply use the
external/libvirt STONITH plugin. It turns out that we only need to be
aware of the hypervisor IP address; all the other information we can
find through node attributes.

Useful resource:
http://www.hastexo.com/resources/hints-and-kinks/fencing-libvirtkvm-virtualized-cluster-nodes
Add attributes and barclamp webui for STONITH
Add validation for stonith bits of the proposal
Generate hostlist for clone stonith