Prevent auto-updater from running when activated

On 4.1RC I'm getting errors triggered by a call in `wp-admin/menu.php` to `wp_get_update_data()` which then tries to call `wp_update_plugins()`, `wp_update_themes()`, and `get_core_updates()` if the user has these caps. The change in this PR removes the capabilities from the user so that these external calls are never made.