recorder: Port to GStreamer 1.0 API

GStreamer developers are currently finishing the 0.11 version, which
will become 1.0. Port the screen recorder to the new API.

https://bugzilla.gnome.org/show_bug.cgi?id=679445

src/test-recorder.c

@@ -1,5 +1,6 @@
 /* -*- mode: C; c-file-style: "gnu"; indent-tabs-mode: nil; -*- */
 
+#define GST_USE_UNSTABLE_API
 #include "shell-recorder.h"
 #include <clutter/clutter.h>
 #include <gst/gst.h>