Better check for timeoutManager api

[Tiberriver256]

The previous check was attempting to check if timeoutmanager is available on the object by determining the OS architecture. I assumed if you were Linux, you were using .net core which meant your version of HttpListener did not contain the timeoutmanager.

Flawed logic... Now I am just checking to see if the member exists and if it does we use it.

Should resolve issue #124

[Tiberriver256]

Interesting... failed tests actually indicate that timeoutmanager is there in .net core but not available for usage on linux architecture. Apparently both checks are necessary.