Comment 9 for bug 1455137

Reviewed: https://reviews.mahara.org/5613
Committed: https://git.nzoss.org.nz/mahara/mahara/commit/e797169819c031a373e39935bb214ab39039fa0a
Submitter: Aaron Wells (<email address hidden>)
Branch: 15.10_STABLE

commit e797169819c031a373e39935bb214ab39039fa0a
Author: Aaron Wells <email address hidden>
Date: Mon Aug 24 18:24:27 2015 +1200

Straightening out the language string situation in the JS calendar (bug 1455137)

The main thing this fixes, is that it causes the JS calendar to use ONLY the
new lang strings pieform_calendar_dateformat & pieform_calendar_timeformat,
for its formatting. These strings are in strftime() format, and are converted
into the JQuery Datepicker/Timepicker format by PHP (if we change to a different
calendar plugin in the future, we can change the PHP conversion function).

This fixes the bug where translators could break the calendar by changing the
JS format strings so they no longer matched the PHP format strings.

As a side effect of this change, I've also made it so that the help strings
are derived from the format string, and are translatable.

behatnotneeded: Date field is already tested by resume_page.feature

Change-Id: I152962cc27f36f93b51ee0327ed942fb089f7f5b
(cherry picked from commit 287b679440f7e2309c17869e04de3940e5affa7d)