FreeSWITCH-FS-6836

Merge pull request #682 in FS/freeswitch from ~WAL-D/freeswitch:bugfix/FS-8775-mod_say_de.c-is-missing-short_date_time to master

* commit 'f6e1056c9417f85024920fd4a6054b8b96b2bcbd':
  FS_8775 Add function SST_SHORT_DATE_TIME to mod_say_de.c and some language tweaks