This reverts commit 84999611, reversing
changes made to 0d9fb211.

- Updated CHANGELOG

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

[ci skip]

Avoids an empty Sign in box when signup_enabled? is false, and avoids
showing "No authentication methods configured" unless there really are none.

OmniAuth signin gets its own file for consistency with signin and signup and LDAP.

We were having the following issues:
- the indicator would sometimes stay red even if the password that was
  entered was long enough;
- the indicator had a middle yellow signal: what does that mean?
- the red/green backgrounds were not color-blind-friendly.

 Fixed a test that was looking for an outdated HTML ID

to the reset password view and the change password view after first login.
Updated JS to work with the updated views.

Fix 500 error on login page if ldap enabled and sign-in disabled

Related to gitlab/gitlabhq#1701

See merge request !1209

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