close #472361: omit password and bytes attributes in allowed mass-mailing keys by fixing default implementation for allowed_massmail_keys() in the Emailable pluggable mixin (cw.common.mixins). Added test (in entities.test though), also fix CWUserTC classes conflicts in the test module.

# server.__init__
"""

:organization: Logilab
:copyright: 2001-2009 LOGILAB S.A. (Paris, FRANCE), license is LGPL v2.
:contact: http://www.logilab.fr/ -- mailto:contact@logilab.fr
:license: GNU Lesser General Public License, v2.1 - http://www.gnu.org/licenses
"""