Appium now responds to the last command it received when instruments exits.

If an iOS app configured to die when sent to the background gets sent to the background during testing, appium does not inform the selenium driver that instruments has exited when the app dies. The selenium driver will wait 60 seconds (the default timeout) until it dies on its own.

This patch allows appium to inform the selenium driver that instruments has exited, thus the selenium driver won't idle until its timeout.

This fixes the issue reported here: https://github.com/appium/appium/issues/1013