iSCSI interface and offload support in Compute

	Note
	iSCSI interface and offload support is only present since Kilo.

Compute supports open-iscsi iSCSI interfaces for offload cards. Offload hardware must be present and configured on every compute node where offload is desired. Once an open-iscsi interface is configured, the iface name (iface.iscsi_ifacename) should be passed to libvirt via the iscsi_iface parameter for use. All iscsi sessions will be bound to this iSCSI interface.

Currently supported transports (iface.transport_name) are be2iscsi, bnx2i, cxgb3i, cxgb4i, qla4xxx, ocs. No configuration changes are needed outside of Compute node.

iSER is currently supported via the separate iSER LibvirtISERVolumeDriver and will be rejected if used via the iscsi_iface parameter.