ifupdown2: add minimal support for bridges

roles/ifupdown2/templates/interfaces.j2

@@ -3,11 +3,27 @@
 {% for name, iface in ifupdown2__interfaces.items() %}
 auto {{ name }}
 iface {{ name }}
-{% for address in iface.addresses %}
+{% for address in iface.addresses | default([]) %}
     address {{ address | ipaddr }}
 {% endfor %}
 {% for gateway in iface.gateways | default([]) %}
     gateway {{ gateway | ipaddr }}
 {% endfor %}
+{% if iface.bridge_ports is defined %}
+    bridge-ports {{ iface.bridge_ports | join(" ") }}
+{% endif %}
+{% if iface.bridge_vlan_aware is defined %}
+    bridge-vlan-aware {{ iface.bridge_vlan_aware
+                         | ternary("yes", "no") }}
+{% endif %}
+{% if iface.bridge_vids is defined %}
+    bridge-vids {{ iface.bridge_vids | join(",") }}
+{% endif %}
+{% if iface.vlan_id is defined %}
+    vlan-id {{ iface.vlan_id | int }}
+{% endif %}
+{% if iface.vlan_raw_device is defined %}
+    vlan-raw-device {{ iface.vlan_raw_device }}
+{% endif %}
 
 {% endfor %}