
Create our own passwd file inside plab vservers.  We add the slice user
to this passwd file, with the password starred out.  This fixes the gaping
security hole resulting from the passwordless root and slice user accounts
that exist in the default plab vserver environment (in conjunction with our
per-vserver sshd).

nmc-probe/emulab-nome,nmc-probe/emulab-nome,nmc-probe/emulab-nome,nmc-probe/emulab-nome,nmc-probe/emulab-nome,nmc-probe/emulab-nome,nmc-probe/emulab-nome,nmc-probe/emulab-nome,nmc-probe/emulab-nome,nmc-probe/emulab-nome,nmc-probe/emulab-nome