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).
Merge pull request #1259 from jaysoffian/remove_unused_get_version

Remove dead "get_version" code