code: function generateCache(filePath) {
      var id = generateIdFromFilePath(filePath);
      Debug._l(id);
      fs.readFile(filePath, 'utf8', function (err, data) {
          if (err) {
              Debug._l("err: " + err);
              return;
          }
          fs.stat(filePath, function (err, stat) {
              setCache(id, {modified:stat.mtime, content:data });
          });
      });
  }
docs: Reads file and cache its data
  @param id
  @param filePath