render error pages using base template

nsupdate/templates/400.html

@@ -1,4 +1,7 @@
-<h1>400 Bad Request</h1>
+{% extends "errorpage.html" %}
 
-This kind of request is not allowed.
+{% block error %}
+<h1>400 Bad Request</h1>
 
+This kind of request is not allowed here.
+{% endblock %}

nsupdate/templates/403.html

@@ -1,5 +1,9 @@
+{% extends "errorpage.html" %}
+
+{% block error %}
 <h1>403 Forbidden</h1>
 
 Sorry, this is not allowed (for you).
 
-If you did not login yet, try logging in.
+If you did not log in yet, try logging in.
+{% endblock %}

nsupdate/templates/404.html

@@ -1,4 +1,7 @@
+{% extends "errorpage.html" %}
+
+{% block error %}
 <h1>404 Not found</h1>
 
 Nothing to see here.
-
+{% endblock %}

nsupdate/templates/500.html

@@ -1,3 +1,7 @@
+{% extends "errorpage.html" %}
+
+{% block error %}
 <h1>500 Internal Server Error</h1>
 
-Sorry :( we screwed up.
+Sorry, we screwed up. Try again later. :(
+{% endblock %}

nsupdate/templates/errorpage.html

@@ -0,0 +1,10 @@
+{% extends "base.html" %}
+{% load i18n %}{% load bootstrap %}
+
+{% block content %}
+    <div class="row">
+       {% block error %}
+       {% endblock %}
+    </div>
+{% endblock %}
+