Fixes #16 and #17

Firstly I know these are very old issues but I've just stumbled across this project and it seems pretty perfect for my needs aside from these two small things.

I looked at the two issues (https://github.com/visionmedia/commander/issues/16 and https://github.com/visionmedia/commander/issues/17) and put the solutions to them (all credit for those goes to @KieranP) into my own fork.

I also fixed a deprecation warning that gets RSpec moans about.