Add Vary header to response

[Aditya Patadia]

🚀 Feature Proposal

Ideally, vary: accept-encoding header should be added to responses which are compressed by this module. If any vary header is already present in response, accept-encoding should be added as comma separated value.

Motivation

https://tools.ietf.org/html/rfc7234#section-4.1 and https://tools.ietf.org/html/rfc7231#section-7.1.4

[Matteo Collina]

Would you like to send a Pull Request to address this issue? Remember to add unit tests.

[Arnovsky]

If possible I'd like to take it.

[Matteo Collina]

go for it!