WIP: Rackconnect v3 Load Balancer Pool support

This provides API support for RackConnect V3 load balancers.  First ask of #104 
I think that this wants to be `with_cmp=False` rather than excluding `nodes` from comparison with `exclude_from_cmp`.  If two `LoadBalancerPool` objects were to have equal `id`/`name`/`port`/`status`/`status_detail`/`virtual_ip`, but *different* `nodes` and a different identity, it seems as though they should compare / hash unequal.  Since the only attribute on `OneLoadBalancerPool` below is `pool`, that means that Klein will be caching any `OneLoadBalancerPool` which *looks* similar as a bound klein resource for a different `LoadBalancerPool` object.

I still haven't figured out if / how this could produce any bad behavior but it nevertheless seems like a good idea to get rid of equality comparison on this mutable object nonetheless.