Using an active logger (not NullLogger) with TestHost results in a null ref

[pranavkm]

From aspnet/Mvc#3796 (comment). Here's the stack trace:

System.NullReferenceException : Object reference not set to an instance of an object.
Stack Trace:
   at Microsoft.AspNet.Http.Internal.DefaultHttpRequest.get_Protocol()
   at Microsoft.AspNet.Hosting.Internal.HostingLoggerExtensions.HostingRequestStarting.ToString()
   at Microsoft.AspNet.Hosting.Internal.HostingLoggerExtensions.HostingRequestStarting.<>c.<.cctor>b__7_0(Object state, Exception exception)
   at Microsoft.Extensions.Logging.Console.ConsoleLogger.Log(LogLevel logLevel, Int32 eventId, Object state, Exception exception, Func`3 formatter)
   at Microsoft.Extensions.Logging.Logger.Log(LogLevel logLevel, Int32 eventId, Object state, Exception exception, Func`3 formatter)

[JunTaoLuo]

Merged to dev