fix account term date processing

test plan:
* visit "/accounts/:account_id/terms"
* term date fields should accept various date formats
as detailed in the ticket (e.g. "MM/DD/YYYY")

closes #CNVS-5177

Change-Id: I5ab41502b5b1598cb2d1dee4f485b2e966e87af3
Reviewed-on: https://gerrit.instructure.com/24245
Tested-by: Jenkins <jenkins@instructure.com>
QA-Review: August Thornton <august@instructure.com>
Reviewed-by: Jeremy Stanley <jeremy@instructure.com>
Product-Review: Jeremy Stanley <jeremy@instructure.com>

Author: maneframe

app/views/terms/index.html.erb

@@ -102,6 +102,11 @@ $(document).ready(function() {
   $(".enrollment_term_form").formSubmit({
     processData: function(data) {
       var permissions = $(this).parents("tr").find(".permissions").getFormData({object_name: 'enrollment_term'});
+      $.each(permissions, function(key, val) {
+        if (key.match(/\[(start)|(end)_at\]/)) {
+          permissions[key] = $.datetime.process(val);
+        }
+      });
       return $.extend(permissions, data);
     },
     beforeSubmit: function(data) {