Improve the Amazon EC2 script.

It now has getopts support, a help message, specifies regions
correctly to avoid manifest errors, and is less verbose.  The
need for sudo will disappear shortly when I integrate some code
from @djs55 that creates the block device from OCaml directly
without needing a loop device.
sync CHANGES
Merge pull request #237 from avsm/ec2-script

Improvements to EC2 deployment script