Added session_persistence property to VIP

Added new property session_persistance to the OS::Neutron::LoadBalancer
resource attribute VIP. Now user can configure session stickness feature
in Neutron LBaaS.

Change-Id: I9afd1a8c222110899a90a940e7a549278c4467b7
Closes-Bug: #1259078
log warning, when $SERVICE_HOST is localhost

Warn users, if heat-keystone-setup can only use localhost as $SERVICE_HOST.
And remove an extra whitespace.

Change-Id: I1b2a1b93212b6ab0ca092bb6c834255ee75176ca
Merge "log warning, when $SERVICE_HOST is localhost"
Merge "Added session_persistence property to VIP"