Add buck configuration file

Change-Id: I8026f58c98eb3682bb018ab410b5818299c991ee

BUCK

diff --git a/BUCK b/BUCK
new file mode 100644
index 0000000..cfbc111
--- /dev/null
+++ b/BUCK
@@ -0,0 +1,4 @@
+gerrit_plugin(
+  name = 'helloworld',
+  srcs = glob(['src/main/java/**/*.java']),
+)