added sync-npm-dependencies script and hooks

package.json

@@ -35,7 +35,8 @@
     "hooks": {
       "pre-commit": "lint-staged",
       "pre-push": "npm test",
-      "post-merge": "npm install"
+      "post-merge": "scripts/sync-npm-dependencies.sh",
+      "post-checkout": "scripts/sync-npm-dependencies.sh"
     }
   },
   "lint-staged": {

scripts/sync-npm-dependencies.sh

@@ -0,0 +1,9 @@
+#!/bin/bash
+
+echo "checking package-lock.json for changes"
+if [ "$1" != "$2" ]; then
+  DIFF=$(git diff $1 $2 package-lock.json)
+  if [ "$DIFF" != "" ]; then
+    npm install
+  fi
+fi