Fix tox config after fa1cf5ef

MANIFEST.in

@@ -15,8 +15,9 @@ recursive-include scripts *
 recursive-include scripts-dev *
 recursive-include tests *.py
 
-recursive-include static *.css
-recursive-include static *.html
-recursive-include static *.js
+recursive-include synapse/static *.css
+recursive-include synapse/static *.gif
+recursive-include synapse/static *.html
+recursive-include synapse/static *.js
 
 prune demo/etc