Feature Request for Range support in Drive client.

Hello,
I am currently using the Drive client and I am trying to do a partial file download stored on a Google Drive account. After spending a few hours I found this as the solution to add the [range](https://stackoverflow.com/questions/36003114/how-to-partial-download-google-drive-files-using-java-rest-client-api) to the HTTP header manually.

I was wondering if the Drive client could support adding the range header to the request itself. The reason is manually touching the HTTP request before sending it increases the likeliness of introducing a bug and generally forces me(the user of the client) to go deeper than I would like too. In general I would say that it is in within the scope of the client to support the adjustment of the HTTP headers being sent to the back-end.

As an example consider the S3Client that Amazon is currently exposing `this.s3Client.getObject(this.getSkeleton.withRange(part.getStart(), part.getEnd()));`. From here I would then actually execute the request and get a stream to that range of the file.

I am not sure if this is entirely out of scope or not so please let me know if this makes sense.
Thank you.