Email based password recovery for the users

This proposal is to enable password recovery for admin and non admin users via email. In this change user will get a “forgot password” link below the login page and user will able to use that link to apply for password recovery. Upon clicking the link, user have to fill their details: username and password and upon submitting the code will check if the username entered is valid or not.
If entered username is valid and user exists then code will check if the entered email address is matches with the email address which user has mentioned. If everything checks out then an email will be sent to the user on their specified email address with a temporary password which they can use to access their account.

This will require the adding support in the Keystone api to enable this functionality and after making changes in the Horizon UI, to add the support for email based password recovery.