Dotmesh release-0.5.0

Implemented #344 - Write a basic dotmesh operator that implement our current Daemonset behaviour.

Various stability fixes to state machines, error handling and debug utilities:
#384 - debug dump RPC
#352 - re-convergence after divergence (still a WIP, probably not release-notes-ready yet)
QUICK FIX didn't get an issue - handle "mount" requests in activeState for quicker startup of new dots
#389: Fixed missing error handling in handoffState, curing a possible deadlock

Note specific upgrade instructions for upgrading etcd and etcd operator in this release: https://docs.dotmesh.com/install-setup/upgrading/#dotmesh-0-4-0-5

Install (docker, kubernetes): https://docs.dotmesh.com/install-setup
Upgrading: https://docs.dotmesh.com/install-setup/upgrading