Samba: Update Bupstash to 0.10.2.

Change-Id: I7d8f62ae6a6391a3147be152aafc21616fe68fb7
diff --git a/images.nix b/images.nix
index 8db4d03..cc6f495 100644
--- a/images.nix
+++ b/images.nix
@@ -161,7 +161,7 @@
       contents = with pkgs; [
         # Services.
         avahi
-        bupstash
+        (callPackage ./samba/bupstash.nix { })
         dbus
         openssh
         #samba4Full