1. 安裝 brew （http://brew.sh/）
/usr/bin/ruby -e "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)"
2. 安裝memcache (https://cnbin.github.io/blog/2015/06/30/install-memcached-on-mac-os-x/)
brew install memcached
3. 運行
memcached -d
4. 安裝client
pip install python-memcached