Add 500 page

app/templates/500.html

@@ -0,0 +1,12 @@
+{% extends "base.html" %}
+
+{% block title %}
+	500 - Internal Server Error
+{% endblock %}
+
+{% block content %}
+	<h1>{{ self.title() }}</h1>
+	<p>
+		Don't worry, this error will have been automatically reported.
+	</p>
+{% endblock %}