Provide the ability to control middleware execution order in the OWIN integration

[alexmg]

The order of middleware is currently determined based on the order of registration. A mechanism needs to be provided to control this order. The ability to add stage markers also needs to be considered when solving this issue.

[tillig]

Stage markers are specific to hosting in IIS, which is probably something we'd want to not involve by default to leave the hosting open.

From the comment chain in this article it appears that registration order is the only ordering mechanism available. Which kind of sucks, but kind of makes sense, too.

As such, I'm not sure we can do too much to aid here other than providing some documentation on how to use the OWIN integration.

[tillig]

For reference purposes, here's the article talking about stage markers in the IIS pipeline.

[tillig]

This issue was moved to autofac/Autofac.Owin#4