Should allow opting out of cookies, and respect DNT header

[julz]

Our current cookie consent flow / about cookies page instructs a user to either disable cookies or use an opt-out browser plugin. We really should allow a user to opt-out via the popup though, and respect the DNT header if set.

[julz]

cc @omerbensaadon

[omerbensaadon]

Ack. Can we move this to docs...?

[julz]

go for it, I put it here because this is where the cookie consent lives currently

[csantanapr]

@julz if you referring to this https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/DNT
Is deprecated