MVC should write content length by default (on IIS)

[danroth27]

Currently MVC responses use chunked encoding by default. This is a bit hard on clients and it also makes for poor error handling when an exception occurs during writing the response content. By default MVC responses should probably be buffered and then have a way to opt into chunked encoding as needed.

[yishaigalatzer]

Fixed by #1074

[yishaigalatzer]

The fix here is to make sure the stream writer doesn't flush the stream upon closing it.
The content length header is generated by IIS and not by MVC.

It is expected that the web listener (self host) will still write chunked results.