Consistent Versioning

[stevesloka]

We should make the versioning consistent across the projectcontour repos. The latest release currently is v2. It would be nice to follow what contour does (e.g. v2.0.0)

[skriss]

Given that we haven't followed semver thus far, I'd like to reset the versioning on the next release to something less than 1.0 -- e.g. v0.4.0, to give a better indication of the stability.