Enable StandardJS auto fix on save

Annoyingly the extension for VSCode doesn't hook into the standard
formatting API but instead uses it's own key bindings so you cannot set
it to format when pressing the format hotkey. Auto fix on save will have
to do for now.

Discussion on the issue tracker here:
standard/vscode-standard#9

.vscode/settings.json

@@ -5,8 +5,5 @@
   "javascript.preferences.quoteStyle": "single",
   "files.insertFinalNewline": true,
   "javascript.validate.enable": false,
-  "editor.defaultFormatter": "standard.vscode-standard",
-  "[javascript]": {
-    "editor.defaultFormatter": "vscode.typescript-language-features"
-  }
+  "standard.autoFixOnSave": true,
 }