EUCA-10018 Add nested stacks for CloudFormation
EUCA-10018 Fixed bugs for nested stack, also ordered describe-stack-events by timestamp and only show for non-deleted stacks in the case where 'name' is passed in.
EUCA-10018 support for Nested stack, which required some tweaking of attribute
validation.

EUCA-9508 only non-deleted stack events are shown when name is passed into describe-stacks.  As an aside, events are sorted by timestamp descending like AWS.
Merge branch 'dev/ethomas/EUCA-10018' into testing