Add epics to nav bar

app/views/layouts/nav/sidebar/_group.html.haml

 - issues = IssuesFinder.new(current_user, group_id: @group.id, state: 'opened').execute
 - merge_requests = MergeRequestsFinder.new(current_user, group_id: @group.id, state: 'opened', non_archived: true).execute
+- epics = EpicsFinder.new(current_user, group_id: @group.id).execute
 
 - issues_sub_menu_items = ['groups#issues', 'labels#index', 'milestones#index']
 - if @group.feature_available?(:group_issue_boards)
@@ -43,6 +44,22 @@
                 %span
                   Contribution Analytics
 
+      -# TODO: Add the flag check to only show epics if available
+      -# TODO: Add epic icon
+      = nav_link(path: 'groups#epics') do
+        = link_to group_epics_path(@group) do
+          .nav-icon-container
+            = sprite_icon('git-merge')
+          %span.nav-item-name
+            Epics
+          %span.badge.count= number_with_delimiter(epics.count)
+        %ul.sidebar-sub-level-items.is-fly-out-only
+          = nav_link(path: 'groups#epics', html_options: { class: "fly-out-top-item" } ) do
+            = link_to group_epics_path(@group) do
+              %strong.fly-out-top-item-name
+                #{ _('Epic') }
+              %span.badge.count.epic_counter.fly-out-badge= number_with_delimiter(epics.count)
+
       = nav_link(path: issues_sub_menu_items) do
         = link_to issues_group_path(@group) do
           .nav-icon-container

ee/app/views/groups/epics/_epics.html.haml

+- page_title "Epics"
+
 %ul.content-list.issues-list.issuable-list