Add Lumen by Laravel

README.md

 ## Micro Frameworks
 *Micro frameworks and routers.*
 
+* [Lumen](http://lumen.laravel.com) - The stunningly fast micro-framework by Laravel.
 * [Silex](http://silex.sensiolabs.org/) - A micro framework built around Symfony2 components.
 * [Slim](http://www.slimframework.com/) - Another simple micro framework.
 * [Bullet PHP](http://bulletphp.com/) - A micro framework for building REST APIs.