Fix NPM issue dep collision with estraverse

npm/npm#9708

Author: zckrs

app/templates/_package.json

@@ -6,6 +6,7 @@
     "test": "gulp test"
   },
   "devDependencies": {
+    "estraverse": "~4.1.0",
     "gulp": "~3.9.0",
     "gulp-autoprefixer": "~3.0.2",
     "gulp-angular-templatecache": "~1.8.0",