Adding a double tagged host in trellis.py
Updating the vagrant file to upgrande linux kernel to 4.15
and install ovs 2.9.2

Change-Id: Ic14f3d79fe65bca07960070f2b6e6151b33e5b7b
diff --git a/trellis/trellis.json b/trellis/trellis.json
index e0aa174..cb945ea 100644
--- a/trellis/trellis.json
+++ b/trellis/trellis.json
@@ -19,12 +19,19 @@
         "of:0000000000000204/5" : {
             "interfaces" : [
                 {
+                    "ips" : [ "10.0.2.254/24" ]
+                }
+            ]
+        },
+        "of:0000000000000204/6" : {
+            "interfaces" : [
+                {
                     "ips" : [ "2000::2ff/120" ],
                     "vlan-untagged": 40
                 }
             ]
         },
-        "of:0000000000000204/6" : {
+        "of:0000000000000204/7" : {
             "interfaces" : [
                 {
                     "ips" : [ "2000::2ff/120" ],