Add download language features
Add download language features

  * Allow single resource file download
  * Warn and skip resources returned with 'Not Found' contents

Auditors: da39a3ee5e6b4b0d3255bfef95601890afd80709@bbondy

luixxiul/browser-laptop,jonathansampson/browser-laptop,timborden/browser-laptop,jonathansampson/browser-laptop,diasdavid/browser-laptop,darkdh/browser-laptop,diasdavid/browser-laptop,diasdavid/browser-laptop,luixxiul/browser-laptop,dcposch/browser-laptop,dcposch/browser-laptop,willy-b/browser-laptop,darkdh/browser-laptop,jonathansampson/browser-laptop,timborden/browser-laptop,pmkary/braver,jonathansampson/browser-laptop,darkdh/browser-laptop,dcposch/browser-laptop,willy-b/browser-laptop,diasdavid/browser-laptop,luixxiul/browser-laptop,pmkary/braver,pmkary/braver,dcposch/browser-laptop,willy-b/browser-laptop,darkdh/browser-laptop,willy-b/browser-laptop,timborden/browser-laptop,pmkary/braver,luixxiul/browser-laptop,timborden/browser-laptop