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/utils/helpers/index.js

@@ -0,0 +1,14 @@
+export * from './dom';
+export * from './errors';
+export { default as exportStore } from './exportStore';
+export { formatInnerLink } from './formatInnerLink';
+export * from './formatManagementTableDate';
+export { default as formatViewsNumber } from './formatViewsNumber';
+export * from './csrfToken';
+export { imageExtension } from './imageExtension';
+export * from './log';
+export * from './math';
+export * from './propTypeFilters';
+export { default as publishedOnDate } from './publishedOnDate';
+export * from './quickSort';
+export * from './requests';