432145 - Pending request is not failed when HttpClient is stopped.

Fixed by fixing the code in close() to also abort pending exchanges.
Reviewed for HTTP, FastCGI and SPDY transports.
432270 - Slow requests with response content delimited by EOF fail.

Fixed by using a flag to determine the need to close the connection,
and by closing the connection only at exchange termination.
Made the test more reliable.
Fixed timeout value left over during debugging.
432270 - Slow requests with response content delimited by EOF fail.

Better handling of the idle case, and closing the connection only
if the response can be failed.
Improved IllegalStateException reporting.