software/re6stnet: Fix slave instance parameters passing and add test

See merge request !983
3 jobs for 1.0 in 0 seconds
Status Job ID Name Coverage
  External
passed SlapOS.Eggs.UnitTest-Master.Python3

01:03:17

passed SlapOS.SlapRunner.ResilienceTest-Master

00:23:38

failed SlapOS.SlapRunner.ResilienceTest-Master.ERP5

00:15:00