Is your feature request related to a problem? Please describe.
When sending files downloaded from GCS back to the user, it would be nice if there existed an option to disable decompressing files that are compressed at rest. Currently we end up decompressing on download (well, this library does) and compressing on the way out to clients again.

Describe the solution you'd like
A flag in file.download() that can disable gzip compression (I absolutely think decompressing should be the default).