nrm - npm源切换管理

安装：npm install -g nrm

显示所有源 `nrm ls`

例如:

* npm ---- https://registry.npmjs.org/
cnpm --- http://r.cnpmjs.org/
eu ----- http://registry.npmjs.eu/
au ----- http://registry.npmjs.org.au/
sl ----- http://npm.strongloop.com/
nj ----- https://registry.nodejitsu.com/

切换源 `nrm use cnpm`

测速 `nrm test`