Update definitions to install CentOS 6.4.
Add dkms package (as was done to the veewee definitions on git).
Install chef via the omnibus installer.
Fix incorrect VirtualBox ostype for the i386 definitions.
Update with CentOS 6.4 boxes.
Add missing nfs-utils on CentOS 6.4 minimal.

Also make ks.cfg better match the default CentOS 6.4 minimal install
version.