Merge branch 'add/buster' into 'master'

Add buster build

See merge request !4
4 jobs for master in 7 minutes and 1 second (queued for 5 seconds)
latest
Status Job ID Name Coverage
  Test Pre Build
passed #6867
test_build_script

00:01:27

 
  Build
passed #6868
build_nginx_buster

00:03:41

passed #6870
build_nginx_jessie

00:05:28

passed #6869
build_nginx_stretch

00:05:33