This patch enables LIO as an iSCSI backend for Cinder, using
python-rtslib.
To enable, set "iscsi_helper = lioadm" in cinder.conf.
This requires python-rtslib 2.1.fb27, which is available from pip.
Implements blueprint lio-iscsi-support
DocImpact
Change-Id: Ifb23de65f26a40997afd6148a1d0be39bcc8d196