[plugins/rabbitmq] Added cluster_status command output

* Added the 'rabbitmqctl cluster_status' output command

Signed-off-by: Jorge Niedbalski R. <niedbalski@gmail.com>
Merge pull request #434 from niedbalski/patch-1

[plugins/rabbitmq] Added cluster_status command output
[corosync/pacemaker] Collect corosync-cfgtool -s output / add Pacemaker support

This patch improves HA clustering information gathering adding a new a
new plugin for Pacemaker.

Signed-off-by: Felipe Reyes <felipe.reyes@canonical.com>
Signed-off-by: Adam Stokes <adam.stokes@ubuntu.com>