gem install cocoapods

gem_install.log

$ gem install cocoapods

CHANGELOG:

## 0.31.1
[CocoaPods](https://github.com/CocoaPods/CocoaPods/compare/0.31.1...0.31.0)
• [CocoaPods-Core](https://github.com/CocoaPods/Core/compare/0.31.1...0.31.0)

##### Minor Enhancements

* The specification now strips the indentation of the `prefix_header` and
  `prepare_command` to aide their declaration as a here document (similarly to
  what it already does with the description).  
  [Fabio Pelosin][irrationalfab]
  [Core#51](https://github.com/CocoaPods/Core/issues/51)

##### Bug Fixes

* Fix linting for Pods which declare a private repo as the source.  
  [Boris Bügling](https://github.com/neonichu)
  [Core#82](https://github.com/CocoaPods/Core/issues/82)


Successfully installed cocoapods-0.31.1
1 gem installed