Changes to run the system behind proxy server

This patch has below changes to support running the system behind proxy server.
This will affect both vagrant and any other environments running behind proxy server.

* Updated Vagrantfile
  * Use proxy_server environment variable to download puppet keys
  * Rerun initial puppet run if not finished successfully.

* Removed keystone::admin_bind_host, keystone::public_bind_host, rjil::test::keystone::public_address,
  rjil::test::keystone::admin_address to make the system work with proxy servers. In case keystone::
  entries are set, certain puppet types in keystone module (keystone_user, keystone_tenant etc) will use that
  IP to connect as keystone endpoint which cause the query to go through proxy server configured. If not set,
  it use localhost, which will avoid proxy server as it is there in no_proxy setting. Same is true for rjil::test
  hiera data.
* Added commented hiera data as examples in vagrant-vbox.yaml to make people easy to setup proxy.
* Contrail code was assuming IP address for contrail api, which was causing vrouter provisioning code
  go through proxy server and it never complete. So changed the code to send dns name rather than IP address,
  and changed contrail module code to resolve to IP address to use whereever required (Some configuration in
  contrail need IP address rather than a dns name.) and to use dns name for vrouter provisioning - service.consul
  is added in no_proxy.
* Updated README.md with instructions to run the system under proxy server.

Note: This PR depends on the PR jiocloud/jiocloud-contrail#26 submitted in jiocloud-contrail