Merge pull request #742 from MatthiasKuehneEllerhold/remove-assetic

Remove deprecated assetic from the recommendations

README.md

 ## Asset Management
 *Tools for managing, compressing and minifying website assets.*
 
-* [Assetic](https://github.com/kriswallsmith/assetic) - An asset manager pipeline library.
 * [JShrink](https://github.com/tedious/JShrink) - A JavaScript minifier library.
 * [Munee](https://github.com/meenie/munee) - An asset optimiser library.
 * [Puli](https://github.com/puli/repository) - A library for determining assets absolute paths.