Show lists to logged out viewers

The activitystreams for lists require a logged in user, so this just
uses a simple database query of all public lists when there is no logged
in user.

bookwyrm/views/list/lists.py

@@ -17,7 +17,10 @@ class Lists(View):
 
     def get(self, request):
         """display a book list"""
+        if request.user.is_authenticated:
             lists = ListsStream().get_list_stream(request.user)
+        else:
+            lists = models.List.objects.filter(privacy="public")
         paginated = Paginator(lists, 12)
         data = {
             "lists": paginated.get_page(request.GET.get("page")),