Use the py27-GitPython package when installing GitPython on FreeBSD.

salt/map.jinja

@@ -48,6 +48,7 @@ that differ from whats in defaults.yaml
       'salt_syndic': 'py27-salt',
       'salt_cloud': 'py27-salt',
       'salt_api': 'py27-salt',
+      'python_git': 'py27-GitPython',
       'config_path': '/usr/local/etc/salt',
       'minion_service': 'salt_minion',
       'master_service': 'salt_master',