Use the py27-pygit2 package when installing pygit2 on FreeBSD

salt/map.jinja

@@ -50,6 +50,7 @@ that differ from whats in defaults.yaml
       'salt_api': 'py27-salt',
       'salt_ssh': 'py27-salt',
       'python_git': 'py27-GitPython',
+      'pygit2': 'py27-pygit2',
       'config_path': '/usr/local/etc/salt',
       'minion_service': 'salt_minion',
       'master_service': 'salt_master',