code: function stop(next) {
      if (phantomProcess) {
          seleniumServerProcess.on('close', function (code, signal) {
              // this should really resolve both callbacks rather than guessing phantom wrapper will terminate instantly
              if (typeof next === 'function' && !seleniumServerProcess ) {
                  next();
              }
          });
          // SIGTERM should ensure processes end cleanly, can do killall -9 java if getting startup errors
          phantomProcess.kill('SIGTERM');
          started = false;
          starting = false;
      }
      if (seleniumServerProcess) {
          seleniumServerProcess.on('close', function (code, signal) {
              if (typeof next === 'function' ) {
                  // need to stub out the other callback
                  next();
              }
          });
          seleniumServerProcess.kill('SIGTERM');
          started = false;
          starting = false;
      }
  }
docs: Stop the servers
  
  @param function optional callback
  @private