git-gui: Improve font rendering on retina macbooks

Signed-off-by: Mads Dørup <mads@dorup.dk>
Signed-off-by: Pat Thoyts <patthoyts@users.sourceforge.net>

Author: cpius

macosx/Info.plist

@@ -24,5 +24,7 @@
 	<string>GITg</string>
 	<key>CFBundleVersion</key>
 	<string>@@GITGUI_VERSION@@</string>
+	<key>NSHighResolutionCapable</key>
+	<true/>
 </dict>
 </plist>