[FIX] Correct remaining SQL now() calls, must use UTC

[FIX] Correct remaining SQL now() calls, must use UTC

This is essential to have the proper behavior for
timestamps: on the database side we exclusively
store UTC data (no DST issues, etc.) as naive
timestamps (to prevent Postgres from messing with them).
Inside OpenERP server/addons we work again with
pure UTC data (much simpler), and only render
them according to the user's timezone when they
are displayed in the user interface or rendered
in a PDF report.

lp bug: https://launchpad.net/bugs/918257 fixed

bzr revid: odo@openerp.com-20120220105943-v3m0i50phrurt8x6