Remove dead "get_version" code

This code dates back to 2aa95f5662 (Display appropriate 'best guess'
version for executing application, 2011-01-03) and is AFAICT completely
unused since at least 75ef8739fe (Move validation logic into coreapi
and remove support for legacy data, 2012-04-08).

I'm pretty sure this code is unused... I don't see anything that populates
this information in the database. I hope I'm not missing anything.