Several changes to support plab nodes on the mainbed:
1) put linktype in the node_auxtypes table instead of having separate classes of vnodes (now they're all one type). 2) Code added to emulabify() to fix the sudoers file pre-overlay. - turns out that only "su" is available to supply initial root access 3) uncapped eligibility to allow all plab nodes to filter in. Other minor things too.