Adding Bazel BUILD files for yang subsystem.

Change-Id: I957cc95d56eb2ddf6906fa4a396ce2556b9b5e86
diff --git a/modules.bzl b/modules.bzl
index cc53368..1efae28 100644
--- a/modules.bzl
+++ b/modules.bzl
@@ -215,8 +215,8 @@
     #"//protocols/restconf/server:onos-protocols-restconf-server-oar",
     #"//apps/restconf:onos-apps-restconf-oar",
     "//apps/flowspec-api:onos-apps-flowspec-api-oar",
-    #"//apps/yang:onos-apps-yang-oar",
-    #"//apps/yang-gui:onos-apps-yang-gui-oar",
+    "//apps/yang:onos-apps-yang-oar",
+    "//apps/yang-gui:onos-apps-yang-gui-oar",
     #"//apps/cord-support:onos-apps-cord-support-oar",
     #"//apps/network-troubleshoot:onos-apps-network-troubleshoot-oar",
     #"//apps/l3vpn:onos-apps-l3vpn-oar",