Add remove WOFF1 script and use in es6 build

Any browser that supports ES6 also support WOFF2, so we can further reduce
distribution size by removing the WOFF1 copies of fonts.

package.json

@@ -47,7 +47,8 @@
     "start": "yarn electron:build && cross-env NODE_ENV=DEV electron .",
     "startFrontend": "ng serve",
     "serveProd": "ng serve --prod",
-    "buildFrontend:prod:es6": "cross-env BROWSERSLIST_ENV='modern' ng build --prod",
+    "removeWOFF1": "find dist/ -type f -iname '*.woff' -delete && find dist/ -type f -iname '*.css' -exec sed -i \"s/, url\\('.*'\\) format\\('woff'\\)//g\" {} \\;",
+    "buildFrontend:prod:es6": "cross-env BROWSERSLIST_ENV='modern' ng build --prod && yarn removeWOFF1",
     "buildFrontend:prod": "ng build --prod",
     "buildFrontend:prodWeb": "ng build --prod --configuration productionWeb",
     "buildFrontend:stage": "ng build --prod --configuration stage",