Remove need for keypair

Certain kinds of environments (PCI, qualysguard, etc) specifically
require you don't use/support shared keypairs, or don't support them.

This removes the need to specify one, which if you're provisioning
instances from images, you'd better have more than one key populated..
Merge pull request #67 from vjanelle/no_keypair

Remove need for keypair
ec2verifysg - verifies cloudcaster spec against live
Merge pull request #69 from WrathOfChris/cm-ec2verifysg

ec2verifysg - verifies cloudcaster spec against live