[IMP] mail, email_template: still continuing work to improve performances of mass...

[IMP] mail, email_template: still continuing work to improve performances of mass mailing.
main differences :
- record_name is not a function field anymore, but a char field + a method in create
if not given (default-like, but dependent of other values). This allows the composer
to give a value for record_name (False for email mass mailing) to avoid browsing
records and having their access rights issues in the way
- author_id, email_from coming from composer instead of called in every mail.message
creation
- moved code dealing with attachments from send_mail to get_mail-values, to that at
the end of this method we know all values of the email

Some tests have been updated / temporarily disabled.

bzr revid: tde@openerp.com-20140224132038-txdi0g30a7fzbnxp