* adds resetTokenValidityDuration setting
* adds a validator to validate password that can be used to enforce strong
passwords
* adds unit tests for passwordPolicy.validator
* adds unit tests to to fail reset password function if password is not in a valid format
* updates README.md for passwordPolicy
* prevents duplicate check for password validator in updateUserPassword
* adds optional setting to disallow username in password
* updates test cases to use fdescribe instead of describe
* updates test cases to use request-promise instead of request
* adds ability to use a RegExp or Callback function or both for a passwordPolicy.validator
* expect username parameter in redirect to password_reset_success
* adds support for _perishable_token_expires_at in postgres
