Allow multiple binds per service in haproxy

The binds parameter in HAProxy can be repeated multiple times to bind to
multiple interfaces/ports. Creating a section called net_binds which
contains a list of optional IP and port parameters to set these.

Change-Id: Iec9fe803786738f3026cf8892c70b76d8fce4305
Prevent duplication of net_binds per service

Almost for all services we will want to use same net_binds.
This is also fits nicely with current haproxy story
As example see this configuration:

{"haproxy": {
    "net_binds": [
        {"ip": "192.0.2.21"},
        {"ip": "198.10.0.32"}
    ],
    "services": [
        {"name" : "horizon",
         "port": 80}
    ],
    "nodes": [
        {"name": "controller0",
         "ip": "192.0.2.23"}
]}}

Which will result in config:

listen horizon
  bind 192.0.2.21:80
  bind 198.10.0.32:80
  mode tcp
  balance source
  option tcpka
  option tcplog
  server controller0 192.0.2.23:80 check inter 2000 rise 2 fall 5

Change-Id: I641fa90c4a34c26e5699cf7f5a6f9643792c7b16
Merge "Allow multiple binds per service in haproxy"
Merge "Prevent duplication of net_binds per service"