i18n Course Activity date fields

fixes: CNVS-11070

Fixes path to the type of date format that needs to be used.  It now uses an
absolute path vs a relative path.

Test Plan:
  - Create a course and update the start at and concluded at
  - Open course activity logs and make sure the dates are in the correct format
    2014-02-10T22:02:42Z 2014-02-10T22:02:42Z should show as Feb 10, 2014 3:02pm

Change-Id: I32f3825254bfcffcceeaa84399b3a89e4bfc75e8
Reviewed-on: https://gerrit.instructure.com/29910
Tested-by: Jenkins <jenkins@instructure.com>
Reviewed-by: Brian Palmer <brianp@instructure.com>
QA-Review: August Thornton <august@instructure.com>
Product-Review: Nick Cloward <ncloward@instructure.com>