refactor: reunite url patterns

Adds option for a trailing "/" when using an extension,
which was not previously supported but should be somewhere
between harmless and a feature.

ietf/meeting/urls.py

@@ -83,8 +83,7 @@ def get_redirect_url(self, *args, **kwargs):
     url(r'^week-view(?:.html)?/?$', AgendaRedirectView.as_view(pattern_name='agenda', permanent=True)),
     url(r'^materials(?:.html)?/?$', views.materials),
     url(r'^request_minutes/?$', views.request_minutes),
-    url(r'^materials/%(document)s/?$' % settings.URL_REGEXPS, views.materials_document),
-    url(r'^materials/%(document)s(?P<ext>\.[a-z0-9]+)$' % settings.URL_REGEXPS, views.materials_document),
+    url(r'^materials/%(document)s(?P<ext>\.[a-z0-9]+)?/?$' % settings.URL_REGEXPS, views.materials_document),
     url(r'^session/?$', views.materials_editable_groups),
     url(r'^proceedings(?:.html)?/?$', views.proceedings),
     url(r'^proceedings(?:.html)?/finalize/?$', views.finalize_proceedings),