[gnome-system-monitor] AppData: Mark as unremovable in GNOME Software

[Richard Hughes <rhughes src gnome org>]

commit a36725aba762bed884bceece1951a84b2bb375e5
Author: Richard Hughes <richard hughsie com>
Date:   Mon Mar 28 16:29:07 2016 +0100

    AppData: Mark as unremovable in GNOME Software

 gnome-system-monitor.appdata.xml.in |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)
---
diff --git a/gnome-system-monitor.appdata.xml.in b/gnome-system-monitor.appdata.xml.in
index c0f8216..087f228 100644
--- a/gnome-system-monitor.appdata.xml.in
+++ b/gnome-system-monitor.appdata.xml.in
@@ -28,6 +28,7 @@
   <url type="homepage">https://wiki.gnome.org/Apps/SystemMonitor</url>
   <updatecontact>robert.roth.off_at_gmail.com</updatecontact>
   <project_group>GNOME</project_group>
+  <compulsory_for_desktop>GNOME</compulsory_for_desktop>
   <translation type="gettext">gnome-system-monitor</translation>
 </application>