Add a class capable of handling lists of fields in resource
body JSON. This is a general purpose class, and is being added
for use in the rsd-lib sushy extension as there are JSON responses
such as {"Initiator": [{"iSCSI": 1}, {"iSCSI": 2}]} that need to
be handled.
Change-Id: Ia5976d8646162e8558dc63584f89e4a3cabbf1f2
262f96e160