0.8.0

This is our first release after moving to our new home at https://howtowhale.github.io/dvm/! 🎉

The documentation and installation have changed a bit. If you are on an older dvm release, run dvm upgrade --version 0.8.0 to get to this intermediate release and from there all future upgrades will look for new releases in the new location. If you run into trouble, repeat the installation steps.

• #152 - Support new Docker release versioning, e.g. 17.3.0-ce.
• Add --pre flag to dvm list-remote to allow listing prerelease versions.
• Update package name to github.com/howtowhale/dvm.