Disposable bootstrapper

Made BootstrapperBase disposable and wired it up to dispose the app container (if it support IDisposable), and wired it into the OWIN hosting, self host and WCF host.

Can't see any way to wire it into the ASP.Net host, but not too concerned as that will be replaced with OWIN/katana soon anyway

Also no idea if WCF will dispose our handler or not, but it's there anyway :)