Fixed TypeLoadException 

This is my first pull request so I hope I get this right.  I ran into the same error as issue#43.  After some research I found this: https://aspnetwebstack.codeplex.com/workitem/1646 .  After a little more work I removed the WebApi.Selfhost package and replaced it with the WebApi.Owin.Selfhost package.  This got rid of the TypeLoadException and I was able to use the self host console app.