fix(admin): Use page_num without +1 (just like django does) (#186)

Author: last-partizan

django_mongoengine/mongo_admin/views.py

@@ -46,7 +46,7 @@ def get_results(self, request):
             result_list = self.query_set.clone()
         else:
             try:
-                result_list = paginator.page(self.page_num + 1).object_list
+                result_list = paginator.page(self.page_num).object_list
             except InvalidPage:
                 raise IncorrectLookupParameters