osx: Implement auto-upgrade function using Sparkle

During the upgrade, NFD and ndn-autoupdate will be stopped (and, if
enabled, automatically started with new versions).

Change-Id: I010ae4a8aa6f99a0039d58065ab7eb0c9189a979
diff --git a/src/Info.plist b/src/Info.plist
index 40eda16..6bb818d 100644
--- a/src/Info.plist
+++ b/src/Info.plist
@@ -33,7 +33,7 @@
     <key>LSUIElement</key>
     <string>1</string>
     <key>SUFeedURL</key>
-    <string>http://named-data.net/binaries/ndn-appcast.xml</string>
+    <string>https://irl.cs.ucla.edu/~cawka/ndn-control-center.xml</string>
     <key>SUPublicDSAKeyFile</key>
     <string>ndn_sparkle_pub.pem</string>
 </dict>