Support multiple simultaneous transfers

[clphillips]

Uploads containing hundreds of files is excruciatingly slow. So it would be nice if we could specify the number of simultaneous transfers (e.g. FileZilla allows between 1 and 10).

    options: {
      path: '/path/',
      host: 'hostname',
      username: 'username',
      password: 'password',
      showProgress: true,
      transferStreams: 2
    }

[sabrehagen]

+1