manager: allow changing password from the user edit form
It should also be possible to generate a password and to send the new password by mail to the user.
utils: add a send templated mail function
It takes an email or an user as first argument then a template name prefix then
a context dictionnary. the following templates are used:
By default if an HTML template is found, it is used to add an HTML version of
the mail. refs #7248.
passwords: add a function to generate password
It can only accomodate A2_PASSWORD_POLICY_MIN_LENGTH and
A2_PASSWORD_POLICY_MIN_CLASSES, it is not possible currently to generate
something that will match A2_PASSWORD_POLICY_REGEX with certainty. It would
need to generate a transducer from the regular expression. refs #7248.