Avoiding some unused headers
Running code cleanup and code analysis
Sorting suppressions
Reorganizing, and implementing some opt-in defacto header support

static helper code for http method override and forwarded headers

extension methods for helper code in different namespace

apply helper code enables site author to modify environment when
needed for overrides to apply to fwks that don't look for them by
default
Merge branch 'master' of https://github.com/loudej/owin-hosting