added missing file

Author: dozoisch

.gitignore

@@ -1,3 +1,3 @@
 node_modules
-lib/
+/lib/
 *.log

tools/lib/build.js

@@ -0,0 +1,16 @@
+import "colors";
+import path from "path";
+import fsp from "fs-promise";
+import { exec, spawn } from "child-process-promise";
+
+const repoRoot = path.resolve(__dirname, "../../");
+const lib = path.join(repoRoot, "lib");
+const src = path.join(repoRoot, "src");
+
+export default function BuildCommonJs() {
+  console.log("Building: ".cyan + "npm module".green);
+
+  return exec(`rm -rf ${lib}`)
+    .then(() => exec(`./node_modules/.bin/babel --optional es7.objectRestSpread ${src} --out-dir ${lib}`))
+    .then(() => console.log("Built: ".cyan + "npm module".green));
+}