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.