v0.25.0 Upgraded dependencies, features, bug fixes

We did it! Another release!

To upgrade: yarn upgrade

Changes: v0.24.0..v0.25.0

Documentation: http://symfony.com/doc/current/frontend.html

Highlights:

• [BC BREAK] Various dependency versions were updated, including
  css-loader updated from ^1.0.0 to ^2.1.1 and resolve-url-loader
  updated from ^2.3.0 to ^3.0.1. The minimum Node version was
  also bumped from 6 to 8. See #540 for more details.

• Added Encore.disableCssExtraction() if you prefer your CSS to
  be output via the style-loader - #539 thank to @Lyrkan.

• Added Encore.configureLoaderRule() as a way to configure the
  loader config that Encore normally handles - #509 thanks to @Kocal.

• Babel cache is no longer used for production builds to avoid a
  bug where the cache prevents browserslist from being used - #516
  thanks to @Lyrkan.