Add Climb

A Composer version manager tool.

README.md

 * [Composer Installers](https://github.com/composer/installers) - A  multi framework Composer library installer.
 * [Pickle](https://github.com/FriendsOfPHP/pickle) - A PHP extension installer.
 * [Melody](http://melody.sensiolabs.org/) - A tool to build one file Composer scripts.
+* [Climb](https://github.com/vinkla/climb) - A Composer version manager tool.
 
 ## Dependency Management Extras
 *Extras related to dependency management.*