http://www.dobervich.com/2011/05/10/less-css-assetic-configuration-in-a-symfony2-project/
http://blogsh.de/2011/09/18/assetic-less/
http://xavierbriand.net/2012/02/09/symfony2-assetic-twitter-boostrap-and-less/
http://www.kiwwito.com/article/less-css-with-assetic-and-symfony-2