Remove LDAP save test

This is handled within the LDAP class
Add regressiontest to verify allow_single_sign_on setting

verification for #1677

Since testing omniauth_callback_controller.rb is very difficult, the logic
is moved to the models
Merge branch 'issue-respect-single-sign-on' into 'master'

Issue respect single sign on

Adds regression test for #1677

See merge request !1188
Refactor error message a bit

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>
Fix account existing blocking

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>
Merge branch 'fix-oauth-block' into 'master'

Fix user being blocked after oauth sign-in

See merge request !1190
Merge branch 'master' into '7-4-stable'

Merge master into 7-4-stable

See merge request !1189