Updated the FAST_SHUTTER guardian to  check ASC-AS_A and ASC-AS_B light levels during shutter test.

The "light on diodes" level is scaled from the trigger PD levels from beckhoff (H1:SYS-MOTION_C_SHUTTER_G_TRIGGER_LOW and H1:SYS-MOTION_C_SHUTTER_G_TRIGGER_HIGH), using a relative gain specified in the FAST_SHUTTER guardian.
The dark limits are specified in in the FAST_SHUTTER guardian.

The changes include:

- A check thet the downstream PD levels are OK when the shutter is open on every lock
- During a fast-shutter test:
    - A check that the downstream PD levels are OK with the shutter open.
    - A check that the downstream PD levels are dark for 9 seconds, starting 0.5 sec after the fast shutter closed.
    - A check that the downstream PD levels are OK after the sutter reopens.

We also tested compatibility with the HAM6 ISI - we seem to trip it a lot on shutter firings when isolated. For now we will leave it damped until after the test.
The guardian was checked into svn as version 14028.