Frontent dev env (#247)

* Added frontend development files/environment

* More items-categories related removals

* Improvements in pages templates (inc. static pages)

* Improvements in video player

* Added empty home page message + cta

* Updates in media, playlist and management pages

* Improvements in material icons font loading

* Replaced media & playlists links in frontend dev-env

* frontend package version update

* chnaged frontend dev url port

* static files update

* Changed default position of theme switcher

* enabled frontend docker container

frontend/config/postcss.config.js

@@ -0,0 +1,10 @@
+module.exports = (ctx) => {
+  const ret = {
+    map: ctx.env === 'development' ? ctx.map : false,
+    plugins: {
+      autoprefixer: {},
+    },
+  };
+
+  return ret;
+};