Add submodule init to default build script

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>
Merge branch 'master' of dev.gitlab.org:gitlab/gitlab-ci
Version 4.3.0

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>
Update guide for 4.3

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