Should namespace appear in the data model?

[aphillips]

In #524 (review), @stasm asked:

Do we want namespaces to be a separate concept in the data model? Or should the data model just store the stringified identifier, i.e. ns:name?

@eemeli replied:

I would prefer not adding namespaces to the data model, and continuing there with a single-string name.

This issue is to discuss whether we should separate namespace in the data model or not.

[aphillips]

Closing in favor of #575