Replaced some read by browse
Moved get_reply_to from mail_mail to mail_message
Hint: specifying email_from, reply_to help to enhance computation time
[REF] mail: cleaned some tests, renamed a file, moved mail_group tests into a dedicated file
bzr revid: tde@openerp.com-20130827133058-ko0g0ib0f0jihmdk
Thibault Delavallée