Add a --version flag

[rgarrigue]

Hi there

Can you add the usual --version flag ? Shouldn't be much work & I'm using those to make sure my install script works

[dsidirop]

Samaritan checking in - I can take up on this errand. It's a standard thing that comes in handy :)

[dsidirop]

Got merged. Will just have to wait for a new release I guess. Maybe we can close this @rgarrigue @wallyqs