Added haproxy for contrail

1. Added rjil::haproxy::contrail to load balance contrail api services
2. Changed rjil::haproxy_service to support different listen and balancer ports
3. Added spec tests.

Changed lb-stats port of haproxy to 8094 as the port 8084 is used by contrail.
Merge pull request #67 from hkumarmk/contrail_haproxy

Added haproxy for contrail