CA-90189: In the case of a dry_run live migrate, skip checking for
missing disks as CDs will be ejected during a real VM migrate.

Signed-off-by: Siddharth Vinothkumar <siddharth.vinothkumar@citrix.com>

Conflicts:
	ocaml/xapi/import.ml
Correcting Indentation

Signed-off-by: Siddharth Vinothkumar <siddharth.vinothkumar@citrix.com>
Merge pull request #1755 from robhoes/ca90189-64

Creedence: backport fix for CA-90189