Switch to m3.medium EC2 types to save a penny or two
Update example images - only 1 arch is needed, and these RHEL AMIs actually don't have requiretty so sudo will work with ssh
Update example comments
You don't need a base AMI to be the same arch as the image you are registering as an AMI
Change SSH username to root, since we're now using RHEL for utility instances
Not all Exceptions have the `value` attribute
Fix referencing of wrong attribute since recent change in AMI list loading
Turns out m2.medium is not valid for EBS -- got mislead by some other docs
Merge branch 'feature/use-rhel-utility-instances' into develop