Update node types to 8

Author: ospatil

generators/app/templates/_package_mocha.json

@@ -29,7 +29,7 @@
   "devDependencies": {
     "@types/chai": "^3.0.0",
     "@types/mocha": "^2.0.0",
-    "@types/node": "^7.0.0",
+    "@types/node": "^8.0.0",
     "chai": "^3.0.0",
     "mocha": "^3.0.0",
     "nyc": "^10.0.0",