Update to Gitlab CI 4.1, use native docker `ADD` instead of bash `curl`, add list of ENV params to read me

Signed-off-by: TruongSinh Tran-Nguyen <i@truongsinh.pro>
Merge pull request #3 from truongsinh/master

Update to Gitlab CI 4.1, use native docker `ADD` instead of bash `curl`,...