slapos-sr-testing: Add caucase

Caucase binaries are required for some testing scenarios.
Status Job ID Name Coverage
  External
passed SlapOS.Eggs.UnitTest-Master.Python2

passed SlapOS.Eggs.UnitTest-Master.Python3

passed SlapOS.SlapRunner.ResilienceTest-Master

failed SlapOS.SoftwareReleases.IntegrationTest-Master.Python2

passed SlapOS.SoftwareReleases.IntegrationTest-Master.Python3