* Add ondelete='cascade' to the res.users.authenticator.create wizard model to
properly support deletion of users who have just created an MFA authenticator
* Slightly reword README
* Replace LasLabs logo with OCA one
* Overload _build_model in res.users model to add two MFA fields to the model
class's list of self-writeable fields, allowing these fields to be edited by
users without admin permissions for their own record
* Update view_users_form_simple_modif and the unit tests in the module based
on the self-writeable field change
* Add relevant fields and methods to the res.users model
* Overload check_credentials in res.users to allow for logins using an MFA
login token rather than a password
* Add the res.users.authenticator and res.users.device models, along with
appropriate ACLs and record rules
* Add the res.users.authenticator.create wizard model and an associated view
to facilitate creation of res.users.authenticator records
* Extend base.view_users_form_simple_modif with fields needed to manage the
new functionality
* Add an AuthTotp controller that inherits from Home in the web module and an
associated view to introduce MFA logic to the login process
* Add several new exception classes that inherit from AccessDenied