Updated user roles
create student_being_graded and student_audited scopes
new scopes in grades controller
change auditing_students to students_auditing
removed ordering scope alpha
move leaderboard students into the controller
fix rank by sorting students as array and add team filter
Updated to remove team filter logic in views
fix scores for course on user
removed todo comment
fixed ordering for top 10 bottom 10
Merge pull request #808 from UM-USElab/user-roles-updated

User roles updated