0233a0e963
Add new 'host_groups' property in inventory files to add hosts to additional Ansible groups. Moreover, add new DEFAULT_HOST_GROUPS env variable which can be used to override the default 'baremetal' group. Finally, add two new variables 'test_vm_default_groups' and 'test_vm_groups' to allow users to set per-vm and default inventory groups when provisioning virtual machines. Change-Id: Id82e63e7049072437a5a8ad5c0300fb29f75ae1f