Feature/add translations

This adds the provided Chinese translation files.  It looks like we've added the JavaScript string `CHOOSE_LANGUAGE` since we sent it over.

In testing, a few strings still seem to be untranslated:
*  City Name
*  Chose File/No file chosen placeholder text (perhaps this is set by browser language?)
*  GTFS
*  'Currently processing in period': text for indicator calculation page
*  Status 'Queued' on indicator calculation page
*  The language names in the 'Choose language' drop-down
*  'Click map to place marker' when adding stops to scenario; also the line-editing tooltips' text