Make DQOK and DQV labels mutually exclusive
The DQOK and DQV labels should be mutually exclusive. When
gwcelery.tasks.detchar.check_vectors adds one of the DQOK or
DQV labels, it will now first remove the other label.
The DQOK and DQV labels should be mutually exclusive. When
gwcelery.tasks.detchar.check_vectors adds one of the DQOK or
DQV labels, it will now first remove the other label.