CLOUDSTACK-2921: Added more logging to attach failure

Also reduced size of attached disk to 1GB

Signed-off-by: Prasanna Santhanam <tsp@apache.org>
(cherry picked from commit ba059dd0ae09f6f7854aef5d14cccb9ce948724b)
CLOUDSTACK-4015: don't insert the fake template record when upgrade from 304 to 305