bumped node engines to >= 8.0.0

Author: fozzleberry

packages/browser-sync/package.json

@@ -18,7 +18,7 @@
     "client/dist"
   ],
   "engines": {
-    "node": ">= 6.0.0"
+    "node": ">= 8.0.0"
   },
   "scripts": {
     "env": "node ./test/env.js",