Update cjdns.sh

1. If cjdroute is not running, 'cjdns.sh stop' pretends it stops cjdroute, but actually does nothing. Corrected this. Now 'cjdns.sh stop' reports that there's nothing to stop and exist with status 1.
2. As per my comment here (https://github.com/cjdelisle/cjdns/pull/250#issuecomment-21322147), 'cjdns.sh update' falls short of restarting cjdroute, falsely reporting that it's already running. I corrected this. Now it updates, stops cjdroute, rechecks PID and starts the updated cjdroute.