Added support for initrd images.

Initrd images are needed by some centos images.  Changed the
timeout for graceful shutdown to 60 seconds, to avoid corruption.

- Added "media=disk,format=raw" to drive specification
- commented out pupptet in sample conf file created by init.
vosa: Added support for configuring networking on centos and debian based configurations.
Made the update disk use media=disk to keep some centos kernels happy