use bootstrap alert classes for messages

gnuviechadmin/templates/base.html

@@ -82,11 +82,12 @@
       <h1>{% block page_title %}Example Base Template{% endblock page_title %}</h1>
 
       {% if messages %}
-      <ul class="list-unstyled">
-        {% for message in messages %}
-        <li{% if message.tags %} class="{{ message.tags }}"{% endif %}>{{ message }}</li>
-        {% endfor %}
-      </ul>
+      {% for message in messages %}
+      <div class="alert alert-dismissible {{ message.tags }}" role="alert">
+        <button type="close" class="close" data-dismiss="alert" aria-label="{% trans "Close" %}"><span aria-hidden="true">&times;</span></button>
+        {{ message }}
+      </div>
+      {% endfor %}
       {% endif %}
 
       {% block content %}