[server] improve TZDatetime support by depending on logilab-database 1.15.0 including https://www.logilab.org/ticket/1485893, we can now keep the tzinfo attribute on datetime objects for TZDatetime attributes, so one knows that this is a tz-aware datetime. To easily make it work with backends that have no tz support, we keep converting tz-aware datetime objects into utc naive datetime objects before sending them to the database.

# -*- 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 precreate script, executed at instance creation time or when
the cube is added to an existing instance, before the schema is serialized.

This is typically to create groups referenced by the cube'schema.
"""