really-reboot-nodes-that-timeout stuff.

NOTE: Until the timeout/retry stuff is gone from os_load/os_setup, it is
disabled in stated. It will still only send email. But all the stuff is
there and has been tested.

NOTE: Until other things don't depend on the old behavior of node_reboot
(when it returns, all nodes are in SHUTDOWN), the event stuff is disabled.
Real mode is the default, and can be run by anyone.

In short, this commit is new versions of stated and node_reboot that act
almost exactly like the old ones. But I wanted to commit them before I go
on making a bunch more changes, to have a checkpoint that I know works.