Revert "View My Scores bug fix #270"

This reverts commit a55798389502afcb7f8f86e5025cd2dfad59a883.

This bug fix was not correct.
Bug fix for #270

Someone renamed the assignment_questionnaires in the Questionnaire
object from assignment_questionnaire to assignment_quesetionnaires.

I renamed this instance variable appropriately in the
compute_weighted_score method.

Finding the assignment questionnaire with AssignmentQuestionnaires.find
seemed like a good solution before, but by using the Questionnaire's
assignment_quesetionnaires foreign key relationship, the total
AssignmentQuestionnaires are actually filtered in scope. This seems
to prevent AssignmentQuestionnaires with the same Assignment id
from being found in this method. Only AssignmentQuestionnaires that
belong to this Questionnaire are searched.
Merge pull request #273 from akofink/master

Bug fix for #270 and #272.