sato: use gtk-play (from gst-player) instead of Gaku

The Gaku media player was always a bit incomplete and had some serious bugs.
gst-player doesn't have these bugs, is maintained, and uses GStreamer 1.x.

(From OE-Core rev: 09fea7f3c0520e555af95234ceb860bd9b4d2878)

Signed-off-by: Ross Burton <ross.burton@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/recipes-sato/packagegroups/packagegroup-core-x11-sato.bb

@@ -49,7 +49,7 @@ WEB ?= ""
 SUMMARY_${PN}-apps = "Sato desktop - applications"
 RDEPENDS_${PN}-apps = "\
     leafpad \
-    gaku \
+    gtk-play \
     x11vnc \
     matchbox-terminal \
     sato-screenshot \