Only show auth response body if verbose is true.
Remove unnecessary request check in sendBody.
Increase client connection timeout to 15s.
Skip possible trailers in chunked body.
Report precise error message to client.
Refactor calcRequestDigest.
Revert "Simplify close server conn after remove channel from map."

This reverts commit c579609c93ff3059deae8ebcdafe0d2f4df3c1e5.

Conflicts:
	conn_pool.go
Lower case for common error messages.