Mention security improvements in CHAGENLOG for 6.3
Mention GitLab CI 4.0 in CHANGELOG

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>
Show only first line of commit message on dashboard

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>
Fix sidekiq start text in documentation and gitlab:check