Need to make easy to track different version of a model in the marketplace

[butler]

Replacing or deleting models from the marketplace is not appropriate since someone may have downloaded it, used it, and pointed to it in their paper. It should thus remain available. However as API's change and more so as users upload modifications (cleaner algorithms, faster integration, more precise results near zero, easier to understand names, etc etc) we need a way to both store this properly in the database and not have an overwhelming array of models many of which are really the same.