Bazel build of ONOS GUI package

Change-Id: Id5f9931c38f82afcdcefc49171dd79f2f5bdad14
diff --git a/tools/gui/BUILD b/tools/gui/BUILD
new file mode 100644
index 0000000..49f18fc
--- /dev/null
+++ b/tools/gui/BUILD
@@ -0,0 +1,6 @@
+exports_files(
+    [
+        "package.json",
+        "gulpfile.babel.js",
+    ],
+)