code: function S3ListObjectStream (options) {
    options = options || {};
    // Important; make this an object stream.
    options.objectMode = true;
  
    S3ListObjectStream.super_.call(this, options);
  }
docs: --------------------------------------------------------------------------- Class constructor. --------------------------------------------------------------------------- 
  @class An object stream to list S3 objects.
  
  Pipe in objects of the following form:
  
  {
  s3Client: new AWS.S3(),
  bucket: 'exampleBucket',
  // Optional, defaults to 1000. How many objects to return in one API
  // request under the hood.
  maxKeys: 1000,
  // Optional. If present, only list objects with keys matching the prefix.
  prefix: 'examplePrefix'
  // Optional. If present, use to group keys.
  delimiter: '/'
  }
  
  Pipe out standard response objects from the S3 listObjects API, with the
  addition of the bucket name as well.
  
  {
  Bucket: 'exampleBucket',
  Key: ...
  LastModified: ...
  ETag: ...
  Size: ...
  StorageClass: ...
  Owner: {
  DisplayName: ...
  ID: ...
  }
  }
  
  @param {Object} options Standard stream options.