Integrating GPS start with dispatcher

[darrylmasson]

Once we have the V1495 FW to support GPS sync starts, we also need an update to the dispatcher to support this. The new logic for starting a run for supported detectors is as follows:

• Is there a GPS sync signal expected between "now" and the next logic loop (min 1 sec)? If yes, send the start command, if no wait for the next cycle.
• Once the start command has been issued, wait until the GPS signal has been logged and then pull it from the db, storing that in the rundoc as the start time (additionally in a new gps_start field with extra precision)

There's probably something I'm missing here, but I think this is a decent start and we'll need something to test with.

[valerioda]

The work on FW upgrade is still on going, Robin is working on it and we proceed as soon as possible.
Looking at dispatcher code changes, it looks ok for me.