Changes for automated build process

This looks like more than it really is because of the two new modules.  Mostly it's just refactoring the build process and moving things around.

- Creates a new Rakefile that is used by the automated build process and updates README to reflect new usage.
- Fixes Vagrantfile and uses standard Centos base box
- Fixes gem caching to recognize pre-cached files from Vagrant or other build tools
- Adds local cache for PE & PE Agent downloads and puppetizes staging
- Implements epel module instead RPM based install
- Moves some of packer build scripts from another repo to be used for possible future packer build.
I'll probably just pull this script out actually.  These scripts are from the old packer build and I'm going to do almost all of that in the rakefile.  It's also done with the staging module now and I added some caching so that packer or vagrant can look for pre downloaded files first.  That said, I'll take a look at adding that check in somewhere.