Issue in case of image is downloaded by the moment of calling pullImageAsync

[maZahaca]

Here is a little issue in the code.
If you run pullImageAsync when an image already exists, it prevents following script execution.

The problem is here:

if (await imageExists(dockerode, imageNameWithTag)) {
      return dockerode.getImage(imageNameWithTag);
}

Should be:

if (await imageExists(dockerode, imageNameWithTag)) {
      resolve(dockerode.getImage(imageNameWithTag));
}