Thanks, Stefanha!
It is not supported at the moment, but as any service could be added which can be hosted by Docker, it is possible to have a one-click git repository. :)
Regarding the buildpacks, I will add more general buildpacks (Heroku's Buildpacks (v2a), Cloudfoundry's Buildpacks (v2b), or the new Cloud Native Buildpack[2], initiative (v3)) like a commenter mentioned here: https://news.ycombinator.com/item?id=30858538.
I'm fully open for contributors!