Converts the option that the preseed file gives into a supplemental
package list by default to avoid accidentally overwriting required
packages.
Also add ipmitool to the supplemental packages list.
1. Remove the respawning and replace with a restart, since it never
worked properly. Also add a "DONE" flag to prevent repeated triggering
during cleanup.
2. Promote the skip_blockcheck to a requested configuration item and a
fully-featured key in the tftp preseed file.
Joshua Boniface