[gnome-calculator] appdata: update license fields

[Michael Catanzaro <mcatanzaro src gnome org>]

commit adc2e01b83acc50a2dd2969384e02e1faa3ff0ca
Author: Michael Catanzaro <mcatanzaro gnome org>
Date:   Fri May 9 20:19:47 2014 -0500

    appdata: update license fields
    
    Also, add the required copyright notice

 data/gnome-calculator.appdata.xml.in |    4 +++-
 1 files changed, 3 insertions(+), 1 deletions(-)
---
diff --git a/data/gnome-calculator.appdata.xml.in b/data/gnome-calculator.appdata.xml.in
index 0597e57..bbd43da 100644
--- a/data/gnome-calculator.appdata.xml.in
+++ b/data/gnome-calculator.appdata.xml.in
@@ -1,7 +1,9 @@
 <?xml version="1.0" encoding="UTF-8"?>
+<!-- Copyright 2013 Michael Catanzaro and contributors -->
 <application>
   <id type="desktop">gnome-calculator.desktop</id>
-  <licence>CC0</licence>
+  <metadata_licence>CC0-1.0</metadata_licence>
+  <project_license>GPL-2.0+ and CC-BY-SA-3.0</project_license>
   <_name>GNOME Calculator</_name>
   <description>
     <_p>