[shotwell] flatpak: Add some indication of being a "nightly"

[Jens Georg <jensgeorg src gnome org>]

commit 00758737abbaafef1695e7a614133982d509a5ba
Author: Jens Georg <mail jensge org>
Date:   Wed Jun 6 11:57:10 2018 +0200

    flatpak: Add some indication of being a "nightly"

 flatpak/org.gnome.Shotwell.json | 2 ++
 1 file changed, 2 insertions(+)
---
diff --git a/flatpak/org.gnome.Shotwell.json b/flatpak/org.gnome.Shotwell.json
index 61dad79a..2cc7f78a 100644
--- a/flatpak/org.gnome.Shotwell.json
+++ b/flatpak/org.gnome.Shotwell.json
@@ -7,6 +7,8 @@
     "rename-desktop-file" : "shotwell.desktop",
     "rename-icon" : "shotwell",
     "rename-appdata-file" : "shotwell.appdata.xml",
+    "tags": [ "nightly" ],
+    "desktop-file-name-prefix": "(Nightly) ",
     "finish-args": [
         "--env=DCONF_USER_CONFIG_DIR=.config/dconf",
         "--filesystem=~/.config/dconf:ro",