Is this going to work for HTTP 2.0?

[christopher-dG]

I haven't been keeping up with anything, but I know HTTP 2 is coming (https://github.com/JuliaWeb/HTTP.jl/pull/1213) and might change some internals. This package basically works via HTTP.pushlayer!, so if the "layer" system no longer exists that will be a problem.

cc @quinnj