Add rules for packaging up Ruby code.

These were originally written by Parker and then cleaned up by me.

Change-Id: I93b66c83f80ca86a267abb84cab5f160b837083b
diff --git a/tools/ruby/BUILD b/tools/ruby/BUILD
new file mode 100644
index 0000000..426a9f1
--- /dev/null
+++ b/tools/ruby/BUILD
@@ -0,0 +1,5 @@
+py_binary(
+  name = 'standalone_ruby',
+  srcs = ['standalone_ruby.py'],
+  visibility = ['//visibility:public'],
+)