interaction with rails serving .gz files

[jjb]

Thanks for a great project!

the readme says:

Before serving a file from disk to a gzip-enabled client, it will look for a precompressed file in the same location that ends in ".gz". The purpose is to avoid compressing the same file each time it is requested.

I believe rails has done this since 4.2.

• https://github.com/rails/rails/commit/cfaaacd9763642e91761de54c90669a88d772e5a
• https://github.com/rails/rails/commit/8e31fa3b72892f7421b85b5a79d71a2d726ccddd

I'm wondering if this project interacts with that behavior appropriately. Might be worth mentioning something in the readme. I can put in a PR for that if the discussion here reveals something interesting.