stop tone and remove audio of failed call

If an incoming call fails due to some error (eg: 503), its ring
tone is never stopped. This stops the ring tone and audio streams
of the call on failure. Otherwise they keep playing and cannot be
stopped by the user without killing the daemon.

Change-Id: I8e3948812fab5d024a9571a99122b452dc4ca092
Tuleap: #1012