Support --verbose

[Duhemm]

Most of the commands expose --verbose to enable verbose logging, but this option is not passed anywhere at the moment.

Enabling verbose logging in Log4J:

Configurator.setRootLevel(Level.DEBUG)

The issue is that we must disable it after the command has run (otherwise, all the commands will run with verbose logging enabled, and there's no obvious place to do it elegantly at the moment.

[jvican]

And likewise we should start using debug sparingly, to have high-quality logs that we can use to keep track of misbehaviours.

[jvican]

Adding this to Bloop 0.2 since it's not high priority.