Update LWR client through LWR changeset db9ea0e6d6a7.
Rework LWR runner parameters to use @natefoo's spec mechanism.
Add new module - galaxy.util.specs - with utilities for things I predict would be common spec types.

This simplifies some things in terms of defaults and empty values that means other simplifications outside the LWR job runner constructor as well (e.g. for ssl_ parameters).
Build on 1ed8dd5 for even simpler LWR param handling.
Refactor amqp_exchange to make shared connection parameters more configurable.
LWR - reuse destination param utility to simply SSL handling.
Allow configuration of more AMQP parameters.

In particular ampq_publish_retry can now be set to True to retry disconnected connections on publication. Hopefully, this will fix producer-related disconnect problems seen in production.