CLOUDSTACK-661
CLOUDSTACK-3930 : Add cleanup

Signed-off-by: Prasanna Santhanam <tsp@apache.org>
CLOUDSTACK-3916: The size test is invalid

ISO size can differ from the mounted packages within the ISO. Remove the
size check and only perform attach and detach in the guest.

Signed-off-by: Prasanna Santhanam <tsp@apache.org>
(cherry picked from commit d875a36e5c79df0f2aea57804dde22a00ba36f7e)