Let info.json provide release/pre-release/build properly

[consideRatio]

I want info.json to categorize the following properly, allowing us to use this json response to generate nice badges for our repository readme files.

This is aligning with development in chartpress. But, there is trouble to debug still with that.

Latest release

x.y.z

Latest pre-releases

x.y.z-alpha.1

Latest build

x.y.z-alpha.1+001.asdf1234
x.y.z+001.asdf1234

[consideRatio]

There was some drama as Helm actually didn't support using the + part of SemVer with the helm repo index command as it considered all the different builds to be the same version and failed to do its merging logic correctly. I pinned down this here: helm/helm#6710

Anyhow, with chartpress version >= 0.4.3, we have a new system of versioning charts where the + sign simply became another . sign. And in 6762a4c i implemented an update to the gh-pages info.json allowing us to get badges like this: