devilryadmin.cmd_simplifiedtestdb: More realistic test data.
devilryadmin.cmd_simplifiedtestdb: More realistic test data.

Added relatedusers that take no assignments, and assignments that not
all students are registered on.

vegarang/devilry-django,devilry/devilry-django,devilry/devilry-django,vegarang/devilry-django,devilry/devilry-django,devilry/devilry-django