[Frontend] Significant re-factoring of CSS and markup

open #95
IN-PROGRESS!;
Mostly buttons and menus classes (s-btn and s-menu);
Removed unused templates and .css files;
Normalized some button containers;

platform/commonUI/general/res/templates/menu/context-menu.html

@@ -20,7 +20,7 @@
  at runtime from the About dialog for additional information.
 -->
 <div class="menu-element context-menu-wrapper mobile-disable-select" ng-controller="ContextMenuController">
-    <div class="menu context-menu dropdown">
+    <div class="menu context-menu">
         <ul>
 
             <li ng-repeat="menuAction in menuActions"