fix serializers, websocket_messaging

gluon/custom_import.py

@@ -8,7 +8,7 @@
 Support for smart import syntax for web2py applications
 -------------------------------------------------------
 """
-from gluon._compat import builtin
+from gluon._compat import builtin, unicodeT, PY2
 import os
 import sys
 import threading
@@ -47,7 +47,7 @@ def custom_importer(name, globals=None, locals=None, fromlist=None, level=-1):
     If the import fails, it falls back on naive_importer
     """
 
-    if isinstance(name, unicode):
+    if isinstance(name, unicodeT) and PY2:
         name = name.encode('utf8')
 
     globals = globals or {}