Make transport_key an optional arg in SecretDTO
Make transport_key an optional arg in SecretDTO

Change-Id: I4ab224e0484c99fbfdf5c6ea3d10e69a8c762d88
Closes-Bug: #1354603

MCDong/barbican,MCDong/barbican,cneill/barbican,cloudkeep/barbican,openstack/barbican,cneill/barbican,jmvrbanac/barbican,openstack/barbican,jmvrbanac/barbican,cloudkeep/barbican