feature request: support grpc health check

[perkfly]

consul supports grpc health check, however I could find grpc in python-consul's docs. Could you please implement the grpc health check type?

[mihaipopescu]

You can do it today just by providing a raw json check:

    result = consul_obj.agent.service.register(
            'service',
            address=service_address,
            port=service_port,
            check={
                'id': 'health',
                'name': 'proxy server health check',
                'grpc': '{}:{}'.format(service_address, str(service_port)),
                'interval': '10s'
            }
        )

but yeah, it would be nice to have library support.