Dotmesh release-0.5.1

• Fix #352 - make divergence recovery more reliable
• Make subdot roots writeable by all users to support container images which run as non-root users
• Implement #305 - initial Prometheus instrumentation of dotmesh-server
• Fix #404 - make push/clone/pull more reliable
• Stop spewing binary data into the logs
• Fix #414 - show correct status for branches in dm dot show
• Fix #403 and #416 - stop pushed dots getting stuck in pushPeerState
• Fix #182 - use go1.10 build caching in containerized builds to bring build times down by 3x
• WIP on #401 to implement PV-per-node mode (not tested, documented or enabled by default yet)
• Fix #373 - always show the progress bar even for very fast transfers

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