remove more no-longer-needed debugging.
whitespace
two new calls to abstract the pattern I peppered all over the place
while debugging.
rewrite wait_for_instances to use new timeout helpers.
format exception a little better.
retry_until_predicate is similar to retry_with_log, just the block is a
check and retries happen if it's not successful, as opposed to throwing
an exception.
refactor EC2 and SG provisioners with new stuff introduced in previous commits.
refactor VPC
refactor with new API.