Convert user & description to string.

Bug reported by Gaël Le Mignot: in a sample case he encountered,
"description" was a unicode object, causing encoding failure in packet
construction.
Python "str" is used in ZODB FileStorage code (see format.py), so just do
the same.

git-svn-id: https://svn.erp5.org/repos/neo/trunk@2167 71dcc9de-d417-0410-9af5-da40c76e7ee4

neo/client/app.py

@@ -728,8 +728,8 @@ class Application(object):
         tid = local_var.tid
         # Store data on each node
         voted_counter = 0
-        p = Packets.AskStoreTransaction(tid, transaction.user,
-            transaction.description, dumps(transaction._extension),
+        p = Packets.AskStoreTransaction(tid, str(transaction.user),
+            str(transaction.description), dumps(transaction._extension),
             local_var.data_dict.keys())
         for cell in self._getCellListForTID(tid, writable=True):
             logging.debug("voting object %s %s", cell.getAddress(),