Convert the job queue rpcs to address-based

Convert the job queue rpcs to address-based

The two main multi-node job queue RPC calls (jobqueue_update,
jobqueue_rename) are converted to address-based calls, in order to speed
up queue changes. For this, we need to change the _nodes attribute on
the jobqueue to be a dict {name: ip}, instead of a set.

Reviewed-by: imsnah