fix two speedgrader i18n issues

fixes CNVS-12953

test plan:
- create an assignment that needs submission and 4 students
- have 3 students submit, grade 2 of them, and have 1 of the graded ones
  resubmit
- check in the speedgrader dropdown, the help text that shows up underneath the
  student names when you hover over them
- there should be 1 each of 'graded', 'not graded', 'not submitted', and
  'graded, then resubmitted...'
- make sure they are localized (i18n)
- also make sure the link to speedgrader for teachers in the right sidebar of
  an assignment page is localized

Change-Id: I62388220f6bd2c0bdf71d79e9d2802ac51db112e
Reviewed-on: https://gerrit.instructure.com/36666
Tested-by: Jenkins <jenkins@instructure.com>
Reviewed-by: Cameron Sutter <csutter@instructure.com>
QA-Review: Amber Taniuchi <amber@instructure.com>
Product-Review: Bryan Madsen <bryan@instructure.com>