Add iSCSI Target resource

Sample target:

configure primitive iscsi_target ocf:heartbeat:iSCSITarget \
        params \
                implementation="tgt" \
                iqn="iqn.2010-07.com.example:storage.disk" \
                tid="1" \
                allowed_initiators="192.168.0.0/24" \
        op start interval="0" timeout="10s" \
        op stop interval="0" timeout="10s" \
        op monitor interval="10s" timeout="10s"

Sample storage device(LUN) /dev/drbd0:

configure primitive iscsi_lun1 ocf:heartbeat:iSCSILogicalUnit \
        params \
               implementation="tgt" \
               target_iqn="iqn.2010-07.com.example:storage.disk" \
               lun="1" \
               path="/dev/drbd0" \
        op start interval="0" timeout="10s" \
        op stop interval="0" timeout="10s" \
        op monitor interval="10s" timeout="10s"

Check configured iSCSI LUNs:

tgtadm --lld iscsi --mode target --op show