Start various services

...and set up dependencies on config files.

Also fixed a mistake in dhcpd.conf.
Cleaned up hard-coded references to ${tftpdir}
Generate ks.cfg via puppet.

The mocpoc::headnode class now requires a slave_rootpw parameter.
puppet modules install centos kernel for slaves.

vmlinuz and initrd.img are placed in /var/lib/tftpboot/centos.

There's now an extra step to get the module ready to go; run make in the
puppet-modules directory. This fetches the above files so they can be
used by puppet.