feat(FreeBSD): add support

syslog_ng/config/file.sls

               }}
     - template: jinja
     - user: root
-    - group: root
+    - group: {{ syslog_ng.rootgroup }}
     - mode: 644
     - require:
       - sls: {{ sls_package_install }}

syslog_ng/defaults.yaml

 # vim: ft=yaml
 ---
 syslog_ng:
+  rootgroup: root
   package: syslog-ng
   service: syslog-ng
   syslog_ng_config: /etc/syslog-ng/syslog-ng.conf

syslog_ng/osfamilymap.yaml

 ---
 Gentoo:
   package: app-admin/syslog-ng
-  service: {{ 'syslog-ng@default' if grains.init == 'systemd' else 'syslog-ng' }}
+  service: {{ 'syslog-ng@default' if grains.get('init', 'unknown') == 'systemd' else 'syslog-ng' }}
 
 Arch:
   service: syslog-ng@default.service
+
+FreeBSD:
+  rootgroup: wheel
+  syslog_ng_config: /usr/local/etc/syslog-ng/syslog-ng.conf