Add OWIN interface, translated to F#.
Switch Owin.fs to use records rather than structs.
Replace the custom HTTP types with the OWIN representations.

Conflicts:

	samples/TestServer/Program.fs
	src/http/HttpParser.fs
	src/http/HttpServer.fs
Add copyright notice.
Complete initial OWIN support.

Conflicts:

	samples/TestServer/Program.fs
	samples/TestServer/packages.config
	src/http/HttpServer.fs
WIP
Update HTTP parser to use OWIN.