Create a CRON job for daily filter restarts

[genghisken]

Occasionally the filter process fails and must be manually restarted. Roy or Gareth have to do this manually at the moment.

We need a CRON job to force daily restarts at (e.g.) the end of the ZTF night or midnight UK.

[RoyWilliams]

The filter process is inside a screen on one of the filter nodes. I don't know how to recreate this with cron.

[gpfrancis]

I've added a try/except to pipeline/filter/filter_runner.py which should trap most of the errors that are causing it to die.