fix(azure-functions) strip headers that are disallowed by HTTP/2
fix(azure-functions) strip headers that are disallowed by HTTP/2

Per https://tools.ietf.org/html/rfc7540#section-8.1.2.2 intermediaries
that proxy HTTP/1.1 responses to HTTP/2 clients should strip certain
headers that do not serve any purpose in HTTP/2. Not stripping these
headers results in a protocol violation for RFC-compliant clients.

See a similar fix for the aws-lambda plugin here:

https://github.com/Kong/kong/commit/f2ee98e2d50d0c70caed4cf19a7a5d48057b9c4f

From #5

Signed-off-by: Thibault Charbonnier <3c2e9133e272cb489e2fea0c4328cf56b08e4226@me.com>

Kong/kong,Kong/kong,Kong/kong