fix missing translation error in due dates

fixes CNVS-5622

updated format on public syllabus to be short
and on the hour

TEST PLAN:
1. Create a course with the public syllabus 
   setting allowed
2. Create multiple sections for the course
3. |Calendar|
4. Click on a day and then change the calendar to 
    the course you just set up for this test
5. |More Options|
6. |"Use a different date for each section"|
7. Set up two dates that are over a month apart
8. |Update Event|
9. Log out and go to the syllabus for that 
    course by using the URL
10 you should see a nicely formatted date

Change-Id: I5de5e1e22152d5f556f50cdc1d067cb44a3e7d09
Reviewed-on: https://gerrit.instructure.com/42226
Tested-by: Jenkins <jenkins@instructure.com>
Reviewed-by: Matthew Wheeler <mwheeler@instructure.com>
Product-Review: Matthew Wheeler <mwheeler@instructure.com>
QA-Review: Steven Shepherd <sshepherd@instructure.com>