Add clean script

Author: bradlc

package.json

@@ -2,7 +2,8 @@
   "name": "root",
   "private": true,
   "scripts": {
-    "bootstrap": "lerna bootstrap --hoist"
+    "bootstrap": "lerna bootstrap --hoist",
+    "clean": "find . -name 'node_modules' -type d -prune -exec rm -rf '{}' +"
   },
   "devDependencies": {
     "lerna": "^3.22.1"