[config] cleanup/refactor server sources file values handling
* kill former `sources` method, misnamed since we've only the system source
configuration in the sources file (and some default admin account information)
* introduce new system_source_config and default_admin_config properties to
access to the two information in this file
Then use one or the other when appropriate
# -*- coding: utf-8 -*-
# copyright %(year)s %(author)s, all rights reserved.
# contact %(author-web-site)s -- mailto:%(author-email)s
#
%(long-license)s
"""%(distname)s views/forms/actions/components for web ui"""