One can now plug its own SMTP server to send notifications
for identity validation and password reset requests.
Filesystem has been removed from the template configuration file
since even tests now use mail catcher (the fake webmail) to
retrieve the email and the confirmation link.
Before this fix, the redirection URL was stored in the user session,
but this has a big drawback since user could open several pages in
browser and thus override the redirection URL leading the user to
be incorrectly redirected.
