Owin.Auto startup support

Haven't made the asp.net hosting package just a metapackage yet, but this is the first step with a new project to support Owin.AutoStartup.

Demo of it can be found here: https://github.com/grumpydev/Nancy.Owin.AutoStartup.Demo

Owin.AutoStartup itself can be found here: https://github.com/grumpydev/Owin.AutoStartup