Update dgbuilder image version

Dgbuilder image should be 0.2-STAGING-latest, not 0.2.1-SNAPSHOT

Change-Id: Ic7ad9efd15a3a31d23f90e9e65a6c7400d7505ff
Issue-ID: SDNC-285
Signed-off-by: Timoney, Dan (dt5972) <dt5972@att.com>