This class manages the versions of your application.
All you need to do is define a version label, assign it an
identifier, export the identifier, and add the version label to the
manager.
Note that Maui.cpp also sets the application's current version.
The intent of this class however is to maintain version history. I
chose to maintain the history in Python since all the code that
cares about version history are the Python feature readers. The
consequence is whenever we bump the application version we need to
make a change in Maui.cpp and this file.
