Add support for GitPython and salt-ssh on FreeBSD masters

This change tweaks the GitPython package installation state to support
alternate package names (on FreeBSD, it's called "py27-GitPython").
Also, on FreeBSD salt-ssh is included in the "py27-salt" package by
default, requiring an update to `distro_map`.

salt/defaults.yaml

   salt_api: salt-api
   salt_ssh: salt-ssh
 
+  python_git: python-git
   python_cherrypy: python-cherrypy
   python_tornado: python-tornado
 

salt/gitfs/gitpython.sls

 {% else %}
 
 python-git:
-  pkg.installed
+  pkg.installed:
+    - name: {{ salt_settings['python_git'] }}
 
 {% endif %}

salt/map.jinja

       'salt_syndic': 'py27-salt',
       'salt_cloud': 'py27-salt',
       'salt_api': 'py27-salt',
+      'salt_ssh': 'py27-salt',
+      'python_git': 'py27-GitPython',
       'config_path': '/usr/local/etc/salt',
       'minion_service': 'salt_minion',
       'master_service': 'salt_master',