Centering of components in horizontal layout

[darenr]

Test case: https://jasonbase.com/things/A2GK

The first template has as the first item a horizontal layout with space - button - button - space. The idea is to center the buttons. The last space components doesn't render. If I change type from space to label it works as expected pushing the buttons into the center.

Updated the json to be smaller. Also tested on the Jason app, this isn't a regression, it doesn't work on master either.