Merge branch 'admin-sidebar-overflow' into 'master'

re-add missing css class in admin sidebar template

See merge request !2759

app/views/layouts/nav/_new_admin_sidebar.html.haml

 .nav-sidebar{ class: ("sidebar-icons-only" if collapsed_sidebar?) }
+  .nav-sidebar-inner-scroll
     .context-header
       = link_to admin_root_path, title: 'Admin Overview' do
         .avatar-container.s40.settings-avatar