Added the last child foreign key and also a root_id property.
Added the last child foreign key and also a root_id property.

PolicyStat/django-threadedcomments,ccnmtl/django-threadedcomments,coxmediagroup/django-threadedcomments,incuna/django-threadedcomments,SmithsonianEnterprises/django-threadedcomments,Almad/django-threadedcomments,nikolas/django-threadedcomments,SmithsonianEnterprises/django-threadedcomments,ccnmtl/django-threadedcomments,coxmediagroup/django-threadedcomments,yrcjaya/django-threadedcomments,nikolas/django-threadedcomments,yrcjaya/django-threadedcomments,HonzaKral/django-threadedcomments,HonzaKral/django-threadedcomments