code: function(key, path, next) {
      this.fileSystem.get(key, function(err, data) {
        fs.writeFile(path, data, function(err) {
          if (err) {
            console.log(err);
          }
          next(err, data); 
        });
      });
    }
docs: currently not used.  was planning on using this function to download files from s3 to reprocess them if the sizes change, but I haven't rewritten that code yet.