make plagiarism scores more visible in student grades page
make plagiarism scores more visible in student grades page

The plagiarism scores were showing up as a dark color on a blue
background but they need to be a light color.  This fixes that.

closes GRADE-703

* Create a course which is vericite enabled and enroll one student
  in it
* Create an assignment that allows online submission and is configured
  for vericite
* Submit a submission as the student and verify it gets a plagiarism
  score
* Go to the student's grades page and verify the plagiarism score
  is now visible as a light color on a blue background

Change-Id: I6eb268c609082833cf18e609105f4aa3723565b6
Reviewed-on: https://gerrit.instructure.com/136590
Tested-by: Jenkins
Reviewed-by: Spencer Olson <7cc0890d6f1f70810a023e7173eca5724d6c8e49@instructure.com>
Reviewed-by: Keith T. Garner <a1a80143a840c140f31c3495ebbd9ec906e09fed@instructure.com>
QA-Review: Anju Reddy <851202533fb1f0b615e4547ba226c76996d060dd@instructure.com>
Product-Review: Keith T. Garner <a1a80143a840c140f31c3495ebbd9ec906e09fed@instructure.com>

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