Haproxy should listen only on vip

Adding ability for haproxy to listen only on specifically configured
vip interface

It will enable setups where using different ports for balancer service
is not convenient, e.g:

listen horizon
  bind 192.168.0.2:80
  balance  source
  mode  http
  server node-1 192.168.0.3:80 cookie node-1  check inter 2000 fall 3
  server node-2 192.168.0.4:80 cookie node-2  check inter 2000 fall 3
  server node-3 192.168.0.5:80 cookie node-3  check inter 2000 fall 3

Related to blueprint tripleo-icehouse-ha-production-configuration

Change-Id: Ifd441a1d5fb50d0cfb16dc4197caf2c1912cf1ab
Make bin/ensure-bridge executable

Make this file executable so that we can make use of it
within the devtest scripts directly.

Change-Id: I4dd7f3c358cc65a7fd9665e4c96005110a3cc011
Merge "Haproxy should listen only on vip"
Merge "Make bin/ensure-bridge executable"