improved dockerfile. improved usage of docker build according to our gitlab CI instace

7 jobs for master in 6 minutes and 48 seconds
Status Job ID Name Coverage
  Scan And Setup
passed #195118
install-dependencies

00:00:54

passed #195117
npm-audit-security-check

00:00:41

 
  Test
passed #195120
lint

00:00:39

passed #195119
retire-security-check

00:01:44

passed #195121
unit-test

00:01:01

 
  Dockerize
passed #195123
privileged
docker-build-and-push

00:02:31

passed #195122
lint-dockerfile

00:00:39