Better Versioning

[adlaika]

Right now, templates are versioned by hand. It would be nice to have something akin to semver, where minor enhancements can propagate to existing uses, but breaking changes can be made without fear of accidentally clobbering stacks--especially important for production.

[adlaika]

One possible solution might be to simply mirror the git history to the template store, though this doesn't solve the minor version issue. It's still not entirely safe anyway--someone could force push and clobber history.