Use HAProxy httpchk for openstack services

Instead of the default TCP connection check use the HTTP check. This
provides a more reliable way to tell if the service is up or not, only
2xx and 3xx response codes will signal a healthy service. This check can
also be used in conjunction with check-ssl to enable checks for services
running SSL/TLS in overcloud.

Change-Id: I1581c091b996422fb1374ea4c024d0a88453e10b
Merge "Use HAProxy httpchk for openstack services"