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/src/static/js/pages/MediaImagePage.js

@@ -0,0 +1,13 @@
+import React from 'react';
+import ImageViewer from '../components/media-viewer/ImageViewer';
+import { _MediaPage } from './_MediaPage';
+
+export class MediaImagePage extends _MediaPage {
+  viewerContainerContent() {
+    return <ImageViewer />;
+  }
+
+  mediaType() {
+    return 'image';
+  }
+}