[gnome-sdk-images/gnome-3-20] Switch to flatpak

[Alexander Larsson <alexl src gnome org>]

commit 86840b4a61dfd1a06df8df394c0903211b8caf26
Author: Alexander Larsson <alexl redhat com>
Date:   Mon May 9 17:38:41 2016 +0200

    Switch to flatpak

 .gitignore |    2 +-
 Makefile   |    3 +--
 2 files changed, 2 insertions(+), 3 deletions(-)
---
diff --git a/.gitignore b/.gitignore
index 29e5c9d..e77eac4 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,4 +1,4 @@
-.xdg-app-builder
+.flatpak-builder
 sdk
 repo
 *~
diff --git a/Makefile b/Makefile
index e99c347..6b3dc76 100644
--- a/Makefile
+++ b/Makefile
@@ -1,6 +1,5 @@
 all: repo org.gnome.Sdk.json
-       rm -rf sdk
-       xdg-app-builder --ccache --require-changes --repo=repo --subject="build of org.gnome.Sdk, `date`" 
${EXPORT_ARGS} sdk org.gnome.Sdk.json
+       flatpak-builder --force-clean --ccache --require-changes --repo=repo --subject="build of 
org.gnome.Sdk, `date`" ${EXPORT_ARGS} sdk org.gnome.Sdk.json
        rm -rf sdk
 
 repo: