brew uses: permit `ls -1` behaviour.

I may be about to be giggled at for one of the most anal PRs I have ever submitted.

Title explains really. This just tweaks the ` brew uses ` command to expel the results in a single column if requested, similar to the behaviour you see if you execute ` ls -1 `.

My Ruby isn't as great as I would love it to be, working on it. Feedback welcome. First proper core contribution, I believe, outside of dealing with the couple Requirements.