Reverting changes from fb8497f9a932a1c56b2c5b331943493e85c71f9c

It seems cssrewrite filter is not working properly with @FooBarBundle notation which is a [known limitation](https://github.com/kriswallsmith/assetic/issues/53). Since useing diffrent notations for `{% javascripts %}` and `{% stylesheets %}` tags unnecessary complicates things I'm reverting to previous notation.