Fix hash code computation for Findings
Fix hash code computation for Findings

71befb56 introduced a regression where we stopped computing hash codes
for new Findings.

rackerlabs/django-DefectDojo,OWASP/django-DefectDojo,OWASP/django-DefectDojo,rackerlabs/django-DefectDojo,rackerlabs/django-DefectDojo,rackerlabs/django-DefectDojo,OWASP/django-DefectDojo,OWASP/django-DefectDojo,OWASP/django-DefectDojo