Support range header to support partial downloads

[blmarket]

Range header is important to support download resume and media streaming. As GetObject supports Range, this commit proxy the range header from the request to Range parameter of the GetObject.

Also found some non-ascii filename caused header to be broken. Added another option to suppress passing the proxied file path.

[blmarket]

If other folks want to try this change before this commit gets merged, use npm i git+https://github.com/blmarket/s3-proxy.git on your project.