Implementing the following functionality: When an instructor tries to add an inactive grader to a group, the system prevents him from doing so and throws a red flash-message saying the user is inactive and thus cannot be added.

Our goal is to be able to determine in the ffront end which groups should be hidden because they are inactive. Our definition of an inactive group is that all of its members are inactive. Thus, (along with the graders associated to each group, which we already passing to the front end) we need to pass the (student) members associated with each group. This will allow the front end for this graders use case to act similarly to the front end of the groups use case (by filtering which groups should be visible or not based on the activity/inacticity of their users)

… display-inactive-graders

Resolve merge conflicts

converting left outer join to inner join, setting default behavior for some hashes (for when trying to access a non-existent key), and adding documentation

A simple rspec test for the Assignment.current_grader_data method that ensures the returned object has the structure required by frontend code to operate correctly.

… display-inactive-graders

Resolve merge conflicts

rspec test that checks the members contained in the object returned by Assignment.current_grader_data is correct.

…/Markus into display-inactive-graders

Fixing merge conflicts

I was initially defining some default behavior for some hashes in the Assignment model, but this was redundant.