更新兩三事…

更新 Ruby Gem

sudo gem update --system

安裝 nvm (node.js)

git clone git://github.com/creationix/nvm.git ~/.nvm
### You can also add this line to ~/.bashrc or ~/.zshrc if you are using zsh
source ~/.nvm  
nvm sync
### Install latest version, you can also specific the version you want
nvm install latest  
### check all versions you installed
nvm ls
### if you need it every time, set it as default
nvm alias default 0.10.20