Remove unfunctional autostart setting

Doesn't do anything, but appears in the settings. I think it was added
accidentally.

Fixes #318.

resources/settings/settings_description.json

@@ -90,15 +90,6 @@
         "default": "",
         "hidden": true
       },
-      {
-        "value": "autostart",
-        "default": "no",
-        "possible_values": [
-          ["no", "no"],
-          ["yes", "yes"],
-          ["minimized", "minimized"]
-        ]
-      },
       {
         "value": "showPowerOptions",
         "default": true,