Suggest optimal groups given a class roster

[mgmodell]

Given a course with students and a target group size, suggests a set of groups such that:

• Every student is a member of exactly one group
• Every group has at least 2 team members
• Group member counts are as close as possible to the target group size
• Minimize the standard deviations of the group diversity scores (group.calc_diversity_score_for_group)
• Minimize fault line strength among groups (ASW a la Calculate fault-line strength using ASW #304)

[mgmodell]

This should include a UI as part of ProjectGroups.tsx through which the user can generate a recommended set of groups (given a target group count), see the diversity scores and fault line strengths and then accept or reject the proposed groups. If accepted, the proposed groups should be created as suggested.

It also must include Cucmber tests.