Update dependency systemjs to v6

Author: renovate-bot

package.json

@@ -19,7 +19,7 @@
     "materialize-css": "^0.100.0",
     "reflect-metadata": "0.1.13",
     "rxjs": "5.5.12",
-    "systemjs": "0.21.6",
+    "systemjs": "6.8.3",
     "zone.js": "0.11.4"
   },
   "devDependencies": {