Ability to target version in updates:run command

[jasonvarga]

Right now it's not very easy to test your update script. When you run the command it'll look at the actual version installed in the composer lock file, which is usually not what you want because you're working on a dev branch and it'll be dev-master instead of the version you haven't released yet.

It would be nice to be able to add php please updates:run --package=1.2.3 --to=1.3.0 to override the version, instead of looking in the lock file.