scifight/models.py: add more validators
scifight/models.py: add more validators

Signed-off-by: Pavel Kretov <7cae407f1f3b56350827d1394be40a3e8f9cb303@gmail.com>

scifight/scifight,turboj55/scifight,scifight/scifight,turboj55/scifight,turboj55/scifight,scifight/scifight