Moving yang files to /models/l3vpn.

Change-Id: I09ef1d727ea638abcd7652f09d42127c9c16c79e
diff --git a/models/l3vpn/BUCK b/models/l3vpn/BUCK
new file mode 100644
index 0000000..babafb0
--- /dev/null
+++ b/models/l3vpn/BUCK
@@ -0,0 +1,4 @@
+yang_model(
+    app_name = 'org.onosproject.models.l3vpn',
+    title = 'L3VPN YANG Model',
+)