BUG-1473: rename yang.model.util.InstanceIdentifier

The class is renamed to InstanceIdentifierType and users are updated to
point to the new name.

Change-Id: I7ece7ea97a4bbbc623156e0e9db692d1e2a56f81
Signed-off-by: Robert Varga <rovarga@cisco.com>
Merge "BUG-1473: rename yang.model.util.InstanceIdentifier"