- giving slices 60 seconds to start isn't realistic. Revert to previous

- giving slices 60 seconds to start isn't realistic. Revert to previous
vserver-init behavior, fork off all vserver init routines (except for
high priority/system slices who can set BACKGROUND=no in their .conf
files, e.g. pl_netflow). vserver exit routines still get 60 seconds to
complete, then they are forcibly killed.
- log stdout/stderr to slice's /var/log/boot.log and close stdin for
their init routines. This may break sensitive SysV init scripts that
assume terminal access.