Add LDAP integration tests
Requires https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/16914
This also requires https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/17048 to make the EE LDAP test pass.
Edited by George Koltsov
Do not update/delete: Banner broadcast message test data
Do not update/delete: Notification broadcast message test data
Requires https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/16914
This also requires https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/17048 to make the EE LDAP test pass.