Allow PMP to switch GPU

This means that we tell OSX not to just force using the high-end
GPU and should result in PMP running on the discrete one more often.

Fixes plexinc/plex-media-player-private#537

bundle/osx/Info.plist.in

@@ -36,5 +36,7 @@
 	<string>True</string>
 	<key>LSMinimumSystemVersion</key>
 	<string>10.9</string>
+	<key>NSSupportsAutomaticGraphicsSwitching</key>
+	<true/>
 </dict>
 </plist>