Fix dhcp-all-interfaces for ubuntu-minimal xenial

The start script of dhcp-all-interfaces currently requires ifup command.
ifup command provided by package ifupdown, which is not installed in
ubuntu-minimal Xenial.

This change adds ifupdown package for debian family, as it required for
dhcp-all-interfaces.

Closes-bug: #1647853

Change-Id: I6dfc0108ec067f350b22e9fb933b9e8d47b09fde

elements/dhcp-all-interfaces/package-installs.yaml

@@ -1 +1,2 @@
 dhcp-client:
+ifupdown:

elements/dhcp-all-interfaces/pkg-map

@@ -8,9 +8,13 @@
     },
     "suse": {
       "dhcp-client": "dhcp-client"
+    },
+    "debian": {
+      "ifupdown": "ifupdown"
     }
   },
   "default": {
-    "dhcp-client": "isc-dhcp-client"
+    "dhcp-client": "isc-dhcp-client",
+    "ifupdown": ""
   }
 }