Add 'auto' version for things installed by apt

[cbednarski]

Some software, like jenkins and mongo, are installed via apt repos and the version changes when upstream releases new stuff. For these, it probably doesn't make sense to have version in the installer.

[cbednarski]

Basically in this case the version should be '' or 'auto' or None and if we find that we should simply accept the any output from the version command. The tricky part is differentiating between exit 1 when the command is missing vs. exit 1 for displaying the version.