remove cssnano so users can run dev without minification

src/css/postcss.config.js

@@ -3,13 +3,6 @@ module.exports = {
    'postcss-import': {},
    'postcss-cssnext': {
 	     browsers: ['last 2 versions', '> 5%'],
-	     },
-    'cssnano': {
-      discardComments: {
-        removeAll: true
-      },
-      minifyFontValues: false,
-      autoprefixer: false
-    }
+	     }
 	}
 };