title: Remove the HTTP_ prefix in Rails headers
body: <p>Any request sent to a Rails controller gets an <code>HTTP_</code> prefixed to it, as that's appended by <code>ActionDispatch::HTTP.Headers</code>. Is there a way to prevent that (without overriding <code>ActionDispatch::HTTP</code>, so that I can use my custom headers, as is and use those as keys for <code>headers.@env</code>?</p>