taskdistribution: Wrap some strings into Binary

As there is no way to assure that stdout, stderr and html_test_result
will have XML-allowed characters, wrap them with xmlrpclib.Binary class, as
suggested in https://docs.python.org/2/library/xmlrpclib.html

erp5/util/taskdistribution/__init__.py

@@ -171,9 +171,17 @@ class TestResultLineProxy(RPCRetry):
             ('duration',  duration),
             ('date',  date),
             ('command',  command),
-            ('stdout',  stdout),
-            ('stderr',  stderr),
-            ('html_test_result',  html_test_result),
+            # Wrap some strings into xmlrpclib.Binary, as they can contain
+            # non-XML allowed characters
+            ('stdout', xmlrpclib.Binary(stdout)
+              if isinstance(stdout, basestring)
+              else stdout),
+            ('stderr', xmlrpclib.Binary(stderr)
+              if isinstance(stderr, basestring)
+              else stderr),
+            ('html_test_result', xmlrpclib.Binary(html_test_result)
+              if isinstance(html_test_result, basestring)
+              else html_test_result),
         ) if x[1] is not None)
         if kw:
             self._logger.info('Extra parameters provided: %r', kw)