Make heat-translator available via python-openstackclient

We had a consensus at the Atlanta Juno Summit that the original design idea of making heat-translator available via python-heatclient is a good way to integrate tool into Heat initially. Once the tool is stable and mature, it can be moved to the heat server side.

This requires more discussion on what's the best possible way to make it happen.

As per the latest discussion at the Vancouver summit, since the python-openstackclient is available to use (which is created as an unified openstack client and comes with pre-built support for some main programs like keystone) and possibly all clients, including python-heatclient, will move to use it with a required plug-in it makes sense to make heat-translator available via python-openstackclient.