ETW and other changes

(1) Added support for ETW tracing. Replaced all tt.idm tracing calls with ETW tracing calls.
(2) Fixed OWIN middleware's challenge behavior for passive mode - challenge must not be added automatically when running in passive mode.
(3) Added code for OWIN middleware to reinstate the original response network stream.
(4) Cleaned up the host-port determination logic - provided a Func delegate with default implementation, which can be overridden when needed.
(5) Removed all references to tt.idm core library, since only place that was using the core library was the hawk server for creating an anonymous principal.