Dotmesh release-0.4.0

Fix #354 - upgrade etcd operator to 0.8.4.
Fix #372 - dm cluster backup-etcd and dm cluster restore-etcd commands to enable backups & restores.
Fix #353 - dm dot show command now shows replication status.

Note specific upgrade instructions for upgrading etcd and etcd operator in this release: https://docs.dotmesh.com/install-setup/upgrading/#dotmesh-0-3-0-4

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