add feature npmrc -r [registry]
Merge branch 'master' of https://github.com/ngenerio/npmrc

* 'master' of https://github.com/ngenerio/npmrc:
  add feature npmrc -r [registry]

Conflicts:
	npmrc.js
Rename china alias to cn.
utf8 vs utf-8
Update -r usage instructions.
Update Readme.
Log 'Using %s registry.' on switching registry.
Tune usage and Readme info about mirrors
Add npm as a keyword.
Tune usage and Readme info about mirrors