add basic distro tests for swarm, swarmmode, dcos (#3957)
add basic distro tests for swarm, swarmmode, dcos (#3957)


jackfrancis/acs-engine,jackfrancis/acs-engine,Azure/acs-engine,Azure/acs-engine,jackfrancis/acs-engine,Azure/acs-engine,Azure/acs-engine,jackfrancis/acs-engine,jackfrancis/acs-engine,Azure/acs-engine