Now invoke the ifcfg-eth99 dhclient hack from
/etc/sysconfig/network-scripts/ifup-emulabcnet,
not directly from ifcfg-eth99, since /etc/init.d/network stop sources
ifcfg-eth99 without telling it why it was sourced.  So, we define a custom
ifup script instead, triggered by the DEVICETYPE variable in
ifcfg-eth99 being set to emulabcnet, and by creating
/etc/sysconfig/network-scripts/ifup-emulabcnet.