Add load balancer to addsvc client

[peterbourgon]

As an example of how to use it.

[jupp0r]

Would you add this to all transport-specific clients separately or refactor them to use a common endpoint abstraction with load balancing injected as middleware?

[peterbourgon]

Good question! I think you'd want to keep the transport-specific clients as separate packages, and wire in the same loadbalancing middleware to each. I think you can do that without significant code duplication. The important thing is to make it easy to use from a consumer perspective: you want to make it a single constructor, ideally from a single package (per transport), and not have to stitch multiple things together in the client-side code. Make sense?

[jupp0r]

Yes. This would probably be easier with #217 implemented.

[jupp0r]

I think this issue can be closed.