Runaway readers

[coderdj]

Sometimes a board crashes. OK, fine. But then when it comes back there are commands lingering in the command DB that tell it to arm, so it does, and it can also be that the S-IN got orphaned up so it starts reading data. All by itself. A few things need to change:

1. On a crash clear all commands from a board that aren't 'stop' maybe (can dispatcher do this on a timeout?)
2. Find some way to ensure S-IN is always low. In principle we should be running in a much more stable way so the ccontrol process should just not go down