add 404 and 500 handlers

apps/amo/templates/amo/404.lhtml

@@ -0,0 +1,40 @@
+{% extends "base_side_categories.html" %}
+
+{% block title %}{{ _('Not Found') }}{% endblock %}
+
+{% block content %}
+{# TODO(jbalogh): reverse these URLs. #}
+{% trans rec="/recommended", search="/search", home="/" %}
+<h1>We’re sorry, but we can’t find what you’re looking for.</h1>
+
+<p>
+  The page or file you requested wasn't found on our site. It's possible that
+  you clicked a link that's out of date, or typed in the address incorrectly.
+</p>
+
+<ul>
+  <li>If you typed in the address, please double check the spelling.</li>
+  <li>
+    If you followed a link from somewhere, please let us know at
+    <a href="mailto:webmaster@mozilla.com"
+       title="Page Not Found on Mozilla.com">webmaster@mozilla.com</a>.
+     Tell us where you came from and what you were looking for, and we'll do
+     our best to fix it.
+  </li>
+</ul>
+
+<p>Or you can just jump over to some of the popular pages on our website.</p>
+
+<ul>
+  <li>Are you interested in a <a href="{{ rec }}">list of recommended add-ons</a>?</li>
+  <li>
+    Do you want to <a href="{{ search }}">search for add-ons</a>? You may go to the
+    <a href="{{ search }}">search page</a> or just use the search field above.
+  </li>
+  <li>
+    If you prefer to start over, just go to the
+    <a href="{{ home }}">add-ons front page</a>.
+  </li>
+ </ul>
+{% endtrans %}
+{% endblock %}

apps/amo/templates/amo/500.lhtml

@@ -0,0 +1,15 @@
+{% extends "base_side_categories.html" %}
+
+{% block title %}{{ _('Oops') }}{% endblock %}
+
+{% block content %}
+{% trans home="/" %}
+<h1>Oops!  We had an error.</h1>
+
+<p>We'll get to fixing that soon.</p>
+<p>
+  You can try refreshing the page, or head back to the
+  <a href="{{ home }}">Add-ons homepage</a>.
+</p>
+{% endtrans %}
+{% endblock %}

apps/amo/views.py

@@ -1,10 +1,11 @@
-import jingo
 import socket
 
 from django.conf import settings
 from django.core.cache import parse_backend_uri
 from django.views.decorators.cache import never_cache
 
+import jingo
+
 
 @never_cache
 def monitor(request):
@@ -41,3 +42,11 @@ def monitor(request):
                         {'memcache_results': memcache_results,
                          'status_summary': status_summary},
                         status=status)
+
+
+def handler404(request):
+    return jingo.render(request, 'amo/404.lhtml', status=404)
+
+
+def handler500(request):
+    return jingo.render(request, 'amo/500.lhtml')

urls.py

@@ -5,6 +5,9 @@ from django.shortcuts import redirect
 
 admin.autodiscover()
 
+handler404 = 'amo.views.handler404'
+handler500 = 'amo.views.handler500'
+
 urlpatterns = patterns('',
     url('^$', 'jingo.views.direct_to_template',
         {'template': 'base.html'}, name='home'),