* Add boot_errno to the nodes table so that nodes can report in a
  subcode to indicate what went wrong. At present, we do not report any
  real error codes; that is going to take some time to work out since it
  will reqiure a bunch of changes to the boot scripts.

* Add new table node_bootlogs to store logs provided by the nodes. Not
  a full console log, but a log of the tmcd client side part. We can
  make it a full log if we want though; just means mucking about with
  the boot phase a bit.

* Add new state transition to NORMALv2 and PCVM state machines. "TBFAILED"
  is a new state that is sent (after TBSETUP) if a node fails somewhere in
  the tmcd client side.

* Change TBNodeStateWait() to take a list of states (instead of single
  state) and an optional pass by reference parameter to return the actual
  state that the node landed in. Change all calls to TBNodeStateWait() of
  course.

* Change os_setup (and libreboot in wait mode) to look for both TBFAILED...