Add a config knob that allows the admin to specify a set of pools that the schedd should always flock to.
Knob MIN_FLOCK_LEVEL sets a minimum value for each submitter's FlockLevel (how many pools in the FLOCK_TO list should receive a submitter ad). The default is 0.
This can be used as a workaround for situations where the FlockLevel is lowered inappropriately (gittrac #7858).
This issue was originally gittrac #7881.