get pid from the Popen instance instead of from get_newest_client_pid

[cursey]

The reason for get_newest_client_pid is because of Morrighan support which launches the client itself (in which case we still want client.exe's pid not morrighan.exe's pid). This change would break support for Morrighan as it is (if running python ./kanan.py -s -m it will return morrighan.exe's pid).

[blookvoodow]

ah, overlooked that, closing the pr