Expiry date on pinned nav cookie

app/assets/javascripts/application.js.coffee

@@ -261,7 +261,7 @@ $ ->
   # Sidenav pinning
   if $window.width() < 1280 and $.cookie('pin_nav') is 'true'
-    $.cookie('pin_nav', 'false', { path: '/' })
+    $.cookie('pin_nav', 'false', { path: '/', expires: 365 * 10 })
     $('.page-with-sidebar')
       .toggleClass('page-sidebar-collapsed page-sidebar-expanded')
       .removeClass('page-sidebar-pinned')
@@ -292,7 +292,7 @@ $ ->
                .toggleClass('header-collapsed header-expanded')
       # Save settings
-      $.cookie 'pin_nav', doPinNav, { path: '/' }
+      $.cookie 'pin_nav', doPinNav, { path: '/', expires: 365 * 10 }
       if $.cookie('pin_nav') is 'true' or doPinNav
         tooltipText = 'Unpin navigation'