Long-Term Organization of This Repo

Now that FHIR 2 has been released, we should consider our long-term organization of this repository. Ideally I'd like to see 4 or 5 tagged releases instead of many branches, one for each of:

- DSTU2
- DSTU3 1.4
- DSTU3 1.6
- DSTU3 1.8
- STU3

Was there a 1.2?