Adding support for connect during service registration

[gtwhite]

We're currently using this library to register service health checks but we're in the process of now building out a service mesh for services to communicate through. This library doesn't support the connect option during service registration (https://www.consul.io/api-docs/agent/service#connect). I've added it on a local build but wondering if there is interest for adding this to the mainline?

[vadim911]

This is a great idea Geren. Thank you for doing this.