Allow user to disable VIP ping resource

Allow user to disable VIP ping resource
if user does not need public network
to be routable.

Since 5.1.1 and 6.0 releases FUEL configures ping resource that checks whether default gateway is accessible in order to fix the corresponding bug:

https://bugs.launchpad.net/fuel/+bug/1370510

Nevertheless, this fix imposes the issue that if user does not have pingable default gateway, deployment of OpenStack cluster will fail as FUEL uses public VIP to configure some of OpenStack entities (e.g. floating ip pools). In order to work this around, user can specify any pingable host as a default gateway, e.g. FUEL master node or apply the patch above and change cluster attribute 'run_ping_checker' to 'false' that will disable the pinger resource. In order to do this user will need to use FUEL CLI and add this parameter manually to the deployment cluster attributes.

Also, be aware that disabling of pinger will introduce back the corresponding bug https://bugs.launchpad.net/fuel/+bug/1370510 

DocImpact
Change-Id: I9e1f29b5ee08ec7276175de213dcdae392251045
Related-bug: #1396126
Merge "Allow user to disable VIP ping resource"