JCLOUDS-602. Added live tests for new EBS volume fields.

While they're implemented in apis/ec2, the tests are in
providers/aws-ec2, generally, to make sure ec2-alike clones won't barf
on them. We're exercising creation of volumes, images and instances
with the new options. I also had to do some sketchy wait-and-loop'ing
in AMIAPILiveTest.testCreateAndListEBSBackedImage() due to what seems
to be a delay on new AMIs showing up in filtered DescribeImages calls,
though they'll show up instantly when you specify the image ID. Go figure.