Set balance to source for openshift_master endpoints
Set balance to source for openshift_master endpoints

Currently the haproxy loadbalancer set by TripleO uses balance
roundrobin. According to this Openshift HA configuration example[1]
it uses balance source for both the API and the router backends.
This way we ensure that all traffic from a user’s session goes to
the same node(sticky sessions).

[1] https://blog.openshift.com/keeping-both-of-your-openshift-container-platforms-highly-available-with-keepalived-and-haproxy/

Change-Id: I6db94513420609a64ac2f2a6238b5eaaea9a7dca

openstack/puppet-tripleo,openstack/puppet-tripleo,openstack/puppet-tripleo