Map vault: install/play count reset for new versions

[JeroenDeDauw]

When uploading a new version of a map using the versioning system, the play and install counts of the map get reset to 0. This does not appear to be happening for mods.

[1-alex98]

Yeah just look at the code and it is wired and yeah looking at the code it makes sense that this happens

[1-alex98]

I would also expect old versions to get deleted

[Sheikah45]

Fixed in #454