CLOUDSTACK-2882: Additional device types for IDE/SCSI

Signed-off-by: Prasanna Santhanam <tsp@apache.org>
(cherry picked from commit b39d302888f965c5c26812b556c2dc395c53bb5c)
CLOUDSTACK-2882: We are mounting an ISO not a volume

So fdisk -l doesn't list the mounted iso. Instead use showmount -e to
find the mounted device.

Signed-off-by: Prasanna Santhanam <tsp@apache.org>
(cherry picked from commit 93f79e1a158cb1f69915a4036f5c1840a38c5e53)