function _copyObject(source, target) {
      var keys = o_keys(source);
      var key;

      for (var i = 0, l = keys.length; i < l; i++) {
        key = keys[i];
        target[key] = source[key] || target[key];
      }
    }
Generates file data of random bytes using the chance.file method for the file name

@param {object}
fileName: String
fileExtention: String
fileSize: Number      <- in bytes
@returns {object} fileName: String, fileData: Buffer