Completed second pass at Stratiform utility.

This commit represents version 2 of the Stratiform utility, and
includes the following changes and/or enhancements:

* Adds a bastion host to VPC creation (Fixes #2)
* Fixes a problem with NAT creation (Fixes #4)
* Tightens up security on the load balancer (Fixes #6)

It also re-organizes and tweaks a bunch of resources and naming
conventions in the templates.  The core Ruby code itself wasn't
modified very much, if at all.