add headless chromium software release

This also adds a headless-chromium component and enables the http_sub
module in the Nginx component. Some basic tests are included. See merge
request !1014 for more details and discussion.
17 jobs for master in 0 seconds
Status Job ID Name Coverage
  External
passed SlapOS.Eggs.UnitTest-Master.Python2

passed SlapOS.Eggs.UnitTest-Master.Python3

passed SlapOS.SlapRunner.ResilienceTest-Master

00:22:50

failed SlapOS.SlapRunner.ResilienceTest-Master.ERP5

00:27:22

failed SlapOS.SoftwareReleases.IntegrationTest-Master.Python3

03:43:48

failed Wendelin.StandaloneDeploymentScriptTest-Debian.Buster.Master

15:03:36

passed SlapOS.Eggs.UnitTest-Master.Python2

passed SlapOS.Eggs.UnitTest-Master.Python2

passed SlapOS.Eggs.UnitTest-Master.Python2

00:08:57

passed SlapOS.Eggs.UnitTest-Master.Python2

00:08:52

passed SlapOS.Eggs.UnitTest-Master.Python2

passed SlapOS.Eggs.UnitTest-Master.Python2

passed SlapOS.Eggs.UnitTest-Master.Python3

passed SlapOS.Eggs.UnitTest-Master.Python3

00:20:14

passed SlapOS.Eggs.UnitTest-Master.Python3

00:33:00

passed SlapOS.SlapRunner.ResilienceTest-Master

00:22:03

failed SlapOS.SlapRunner.ResilienceTest-Master.ERP5

00:24:58