[FIX] email_template: missing translations in email template

When composing an email based on an email template, some parts of the template
(the result of name_get on fields) were not translated.
This was due to missing language in context when rendering the template.
Fixes #3708, opw 617309
[IMP] ir_mail_server: Set an OpenERP alias as the bounce address.

Fixes issue #3347.