Mac OX 10.10 cocoapods升级步骤

1. Uninstall cocoapods
   $ sudo gem uninstall cocoapods
2. Uninstall xcodeproj $ sudo gem uninstall xcodeproj
3. Install xcodeproj
   $ sudo gem install xcodeproj
4. Install cocoapods
   $ sudo gem install cocoapods
5. Run pod --version to verify that it worked

warning: Insecure world writable dir /usr/local/bin in PATH, mode 040777，解决方法

sudo chmod go-w /usr/local/bin