Fixes error pages

bookwyrm/templates/404.html

@@ -0,0 +1,11 @@
+{% extends 'layout.html' %}
+{% load i18n %}
+
+{% block title %}{% trans "Not Found" %}{% endblock %}
+
+{% block content %}
+<div class="block">
+    <h1 class="title">{% trans "Not Found" %}</h1>
+    <p>{% trans "The page you requested doesn't seem to exist!" %}</p>
+</div>
+{% endblock %}