XCAT- Add nodes to group and get list of nodes added in a group.

This change includes:
    Adding BMC nodes to a group
    Verify added BMC nodes
    Get list of nodes added in a group.

This resolves openbmc/openbmc-test-automation#657

Change-Id: I9bd9668cfe8605728113d9f4f92cf5f7b64f4a68
Signed-off-by: Prashanth Katti <prkatti1@in.ibm.com>
3 files changed