CocoaPods 本來作為一個第三方庫管理工具，有的時候總是出現各種莫名其妙的問題，最近遇到一個問題就是:
The `master` repo requires CocoaPods 1.0.0 - (currently using 0.39.0)
中間折騰了很久，受啟發的有兩篇文章:
http://blog.cocoapods.org/Sharding/
cd ~/.cocoapods/repos/master/
git fetch origin master
git checkout v0.32.1
CocoaPods 0.39.0 不能setup不能通過原本的source "https://github.com/CocoaPods/Specs.git" 進行更新，需要指定Tag，0.32.1.
另外一篇文章https://github.com/CocoaPods/CocoaPods/issues/6164,解決方案與上面類似:
cd ~/.cocoapods/repos && git clone https://github.com/CocoaPods/Specs.git && cd specs && git checkout v0.32.1)
, or upgrade to CocoaPods > 1.0
