Update deps, bump extensionBundle to v4 (#80)

Author: jakebailey

host.json

@@ -10,6 +10,6 @@
   },
   "extensionBundle": {
     "id": "Microsoft.Azure.Functions.ExtensionBundle",
-    "version": "[3.15.0, 4.0.0)"
+    "version": "[4.0.0, 5.0.0)"
   }
 }