Fixed sample to deal with due dates appropriately
Merge pull request #821 from UM-USElab/sample-fix

Fixed sample to deal with due dates appropriately
Reduced time of sample data slightly, added team challenges back to course form
Merge pull request #822 from UM-USElab/course-challenges

Reduced time of sample data slightly, added team challenges back to cour...
Updated sample
Merge pull request #823 from UM-USElab/sample-updates

Updated sample
Refactored mass_update to improve response time, moved caching scores to a background worker and refactored mass_edit to use eager loading (fixed 1+N problem that was hidden in the edit view) and significally improved response time
Added a Hash helper method to find a nested key values
Switched student_id to student
Lazy created grades for no grades students and auditors