Added commander banned/no commander list capability

Per issue #1, this implements the legality for commander.  I updated the legality.json file (updated version hosted here: https://dl.dropboxusercontent.com/u/8334514/legality.json) and had to add a new type of legality for the cards that are not banned/restricted, but cannot be used as commander.  Keeping with the existing naming convention, I named the option "NoCommanderList".