This is an example of versioning APIs by dates of changes released opposed to using strictly the URL. This prevents duplicate code for functionality that has not changed in a new release.
This is more of a proof of concept example than a ready to use project. It is by no means finished or production ready. If you are going to use anything from this project, use the concepts taken from the source.
The example is explained better on my blog @ API Versioning - Using Date Released.