display flashed messages

app/templates/base.html

@@ -3,7 +3,17 @@
 {% block title %}Prolefeeder{% endblock %}
 {% block content %}
 <div class="container">
+
+{% with messages = get_flashed_messages() %}
+{% if messages %}
+    {% for message in messages %}
+    <div class="alert alert-info" role="alert">{{ message }}</div>
+    {% endfor %}
+{% endif %}
+{% endwith %}
+
 {% block app_content %}
 {% endblock %}
+
 </div>
 {% endblock %}