Pana/nrm — pull request #3 by Jeremial (2014-04-12 13:52:25+00:00)
Title: use commander and other npm modules to refactor nrm

1. auto output help infomation
2. use npmconf instead of spwan to save npm registry config
3. save user's custom registry info to $HOME/.nrmrc, seprate from nrm's config
4. only allow to delete custom registry config