Add CommonJS export (James Pickard)

commit d6d2748687a636ff1da9c9ba3bc3b5b4b68187aa
Author: James Pickard <james.pickard+github@gmail.com>
Date:   Fri Jan 18 17:04:46 2013 -0500

    fix comment

commit 2b25e6a0bae63071fa0a9b6b09f28b28873ca942
Author: James Pickard <james.pickard+github@gmail.com>
Date:   Fri Jan 18 16:44:22 2013 -0500

    add CommonJS export