[6.1 / trunk] survey module not fully unicode aware

Hello,

When using non-ascii characters in survey answers (for fields of type comment), the surveys cannot be viewed using the "Browse Answer" function.

How to reproduced in 6.1:
1. openerp 6.1 with survey module and demo data
2. Go to Tools > Surveys > Answer Surveys > Answer a Survey
3. Select survey "Initial Partner Feedback"
4. On page 2 enter accents (é, for instance) for question "Why?"
5. clock done
6. Go to Tools > Reporting > Surveys > Browse Answers
7. Select survey "Initial Partner Feedback"
8. click next and you get the following stack trace

OpenERP Server Error
Client Traceback (most recent call last):
  File "/opt/openerp/web/6.1/addons/web/common/http.py", line 180, in dispatch
    response["result"] = method(controller, self, **self.params)
  File "/opt/openerp/web/6.1/addons/web/controllers/main.py", line 1065, in default_get
    return Model.default_get(fields, req.session.eval_context(req.context))
  File "/opt/openerp/web/6.1/addons/web/common/openerplib/main.py", line 250, in proxy
    args, kw)
  File "/opt/openerp/web/6.1/addons/web/common/openerplib/main.py", line 117, in proxy
    result = self.connector.send(self.service_name, method, *args)
  File "/opt/openerp/web/6.1/addons/web/common/http.py", line 608, in send
    raise xmlrpclib.Fault(openerp.tools.exception_to_unicode(e), formatted_info)

Server Traceback (most recent call last):
  File "/opt/openerp/web/6.1/addons/web/common/http.py", line 593, in send
    return openerp.netsvc.dispatch_rpc(service_name, method, args)
  File "/opt/openerp/server/6.1/openerp/netsvc.py", line 360, in dispatch_rpc
    result = ExportService.getService(service_name).dispatch(method, params)
  File "/opt/openerp/server/6.1/openerp/service/web_services.py", line 586, in dispatch
    res = fn(db, uid, *params)
  File "/opt/openerp/server/6.1/openerp/osv/osv.py", line 167, in execute_kw
    return self.execute(db, uid, obj, method, *args, **kw or {})
  File "/opt/openerp/server/6.1/openerp/osv/osv.py", line 121, in wrapper
    return f(self, dbname, *args, **kwargs)
  File "/opt/openerp/server/6.1/openerp/osv/osv.py", line 176, in execute
    res = self.execute_cr(cr, uid, obj, method, *args, **kw)
  File "/opt/openerp/addons/6.1-fixes/audittrail/audittrail.py", line 495, in execute_cr
    return fct_src(cr, uid, model, method, *args)
  File "/opt/openerp/server/6.1/openerp/osv/osv.py", line 164, in execute_cr
    return getattr(object, method)(cr, uid, *args, **kw)
  File "/opt/openerp/addons/6.1-fixes/survey/wizard/survey_answer.py", line 502, in default_get
    value[field] = str(que.comment)
UnicodeEncodeError: 'ascii' codec can't encode character u'\xe9' in position 0: ordinal not in range(128)