roles/samba: Support selecting interfaces

The `samba_interfaces` variable can now be defined to populate the
`interfaces` global configuration parameter in `smb.conf`. This
parameter controls the interfaces or addresses to which the Samba server
binds, and also the IP addresses that are registered in DNS.

roles/samba/templates/smb.conf.j2

@@ -11,6 +11,10 @@ server role = {{ samba_server_role }}
 {% else %}
 security = {{ samba_security }}
 {% endif %}
+{% if samba_interfaces is defined %}
+
+interfaces = {{ samba_interfaces|join(' ') }}
+{% endif %}
 {% if samba_options is defined %}
 
 {% for option in samba_options %}