Diablo is long gone. Remove debs for diablo nova volumes
Original commit that added this: I3e7c412ff125dbadd18b59af55fb7dea9ea17b07
Move open-iscsi requirement over to ironic, (ironic conductor calls
iscsiadm)
libvirt driver uses iscsiadm for iscsi based volume attaches as well.
lvm backend is supported for libvirt driver
Change-Id: I536ba0ebdb6e3fa68f0a82b3027e70d8e2f35085