Fix rake gitlab:ldap:check

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>
Make gitlab ldap check work for old and new syntax

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>
Merge branch 'stable-fix-ldap-check' into '7-4-stable'

Fix ldap check [stable]

Fix ldap check for stable branch

See merge request !1208
Merge branch 'fix-500-login-disabled' into 'master'

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

Related to gitlab/gitlabhq#1701

See merge request !1209
Version 7.4.0.