add rails flash messages that dismiss after 5 seconds

app/views/layouts/application.html.erb

@@ -51,6 +51,16 @@ with BigBlueButton; if not, see <http://www.gnu.org/licenses/>.
     style="background-image:url(<%= image_path('greenlight_background.png') if params[:controller] == 'landing' %>);">
     <!-- Messages -->
     <div id='alerts'>
+      <div class='flash-alerts'>
+        <% flash.each do |name, msg| %>
+          <div class="alert alert-<%= name %> alert-dismissible fade in" role="alert">
+            <button type="button" class="close" data-dismiss="alert" aria-label="Close">
+              <span aria-hidden="true">&times;</span>
+            </button>
+            <span class="alert-message"><%= msg %></span>
+          </div>
+        <% end %>
+      </div>
     </div>
 
     <!-- Header -->