Rework connection handling for better resilience

* Include a suite of network failure tests using a TCP proxy
* Run all operations in a retry loop
* Separate consumer and pool connection handling
* Manage producers ourselves
More tests
Delete call RPC queue after use
Refine handler error logging

Don't log so noisily for known dashi errors
gitignore coverage
Bump kombu dep to >=2.5.0
Update versions and fix setup.py bug