[gnome-sdk-images] Ensure we load sdk extensions for version 1.6

[Alexander Larsson <alexl src gnome org>]

commit c9d0d627de2a8b765cb68c0eeb5210ef544671af
Author: Alexander Larsson <alexl redhat com>
Date:   Tue Apr 4 15:49:32 2017 +0200

    Ensure we load sdk extensions for version 1.6

 org.gnome.Sdk.json.in |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)
---
diff --git a/org.gnome.Sdk.json.in b/org.gnome.Sdk.json.in
index 279ace8..9e4e15e 100644
--- a/org.gnome.Sdk.json.in
+++ b/org.gnome.Sdk.json.in
@@ -27,6 +27,7 @@
         "--extension=org.freedesktop.Sdk.Extension=subdirectories",
         "--extension=org.freedesktop.Sdk.Extension=directory=lib/sdk",
         "--extension=org.freedesktop.Sdk.Extension=no-autodownload=true",
+        "--extension=org.freedesktop.Sdk.Extension=version=1.6",
         "--env=GI_TYPELIB_PATH=/app/lib/girepository-1.0",
         
"--env=GST_PLUGIN_SYSTEM_PATH=/app/lib/gstreamer-1.0:/usr/lib/extensions/gstreamer-1.0:/usr/lib/gstreamer-1.0",
         "--sdk=org.gnome.Sdk//@@SDK_BRANCH@@",