[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.
bgcolor = '#000000'
stylesheets = ['%s/cubicweb.css' % datadir_url]
logo = '%s/logo.png' % datadir_url
lazy = lazystr('%(bgcolor)s')