fixes #1594 Create categories all at once, then show them when needed, t...

...his ensures the order they are in when we create them is the order they get displayed in
Can you add a `.brick-category` prefix to this selector? The rest of this code uses stuff like https://github.com/ScottDowne/appmaker/blob/t1594/public/designer/js/component-tray.js#L214 .