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.
 * [Pipe](https://github.com/CHH/pipe) - Another asset manager pipeline library.