Refs #13047 and #12980 -- Fixed es_AR message format specifiers:

 * Reviewed them for missing backslash escaping characters.
 * Converted all of them to raw strings for consistency.
 * Made default 'long' output specifiers for dates and/or times more terse
   and so more suited to real local usage, trying to maintain backward
   compatiblity with the equally named pre 1.2 technical message IDs where
   possible.

Thanks to Fabián Ramirez for his work on this.


git-svn-id: http://code.djangoproject.com/svn/django/trunk@13045 bcc190cf-cafb-0310-a4f2-bffc1f526a37