After seeing the following graph [here](http://sweetme.at/2013/09/11/how-to-maximize-png-image-compression-with-optipng/) we decided to test optimsation level 2 for OptiPNG instead of 7. This is because, acording to the graph we would notice no real difference in avarage file size but would notice a speed increase with our builds.
After testing , we noticed our theme build go from a build time of over 10 mins (just on the 94% asset optimisation step) to an avarage of `150.75s`. All the while, we only gained 10-15kb per png file which we believe more than reasonable for a build speed increase of this magnatude.
Using `merge.smartStrategy` with `'module.loaders' = 'replace'` to load
the preset config allows presets to override the the default webpack
config. This is necessary for the coming Tailwind preset which requires
`resolve-url-loader` and source maps to be disabled.
* Add uglifyjs plugin and replace -p flag with --env.production
* Add uglifyjs plugin
* Configure UglifyJsPlugin to drop console and prevent eslint error
* Turn off no-console rule because uglifyjs plugin drops it in prod
- Removed unnecessary url-loader targeting .woff files
- Replaced file-loader with url-loader (file is fallback for url)
- PostCSS plugins are all loaded manually vs postcss.config.js
