Running `rubyfmt` with no args hangs

[dbalatero]

If you run rubyfmt, it just hangs there and appears to be trapping ctrl c and not exiting:

My expectation was that it would print out help when no arguments are passed. If that's not desired behavior, fixing ctrl c would be great so exiting is possible without doing a kill -9. Thanks!

[reese]

Fixing this in #376 -- it doesn't fix the signal handling bits, but I'll leave that to be fixed as part of #322.