Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

This makes it consistent with the Invalid email/password error message
from the previous step.

Also adds test case for providing an invalid 2FA code and then a valid
one without re-entering username and password.

"Two-factor" vs. "2-Factor"

Turn 2-factor authentication into 2 steps process. Disabled 2fa UI for ldap users since it is not supported

Remove class and id attributes from SanitizationFilter whitelist

Closes internal https://dev.gitlab.org/gitlab/gitlabhq/issues/2302

See merge request !631