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/templates/static/signoutPage.html

@@ -0,0 +1,20 @@
+<div id="app-header"></div>
+<div id="app-sidebar"></div>
+<div class="page-main-wrap">
+  <div class="page-main">
+    <div class="page-main-inner">
+      <div class="user-action-form-wrap">
+        <div class="user-action-form-inner">
+          <h1>Sign Out</h1>
+          <p>Are you sure you want to sign out?</p>
+          <form method="post" action="#">
+            <input type="hidden" name="csrfmiddlewaretoken" value="" />
+            <button type="submit">Sign Out</button>
+          </form>
+        </div>
+      </div>
+    </div>
+    <div class="page-sidebar-content-overlay"></div>
+  </div>
+</div>
+<div id="app-footer"></div>