Fix no-theme bug in Onboarding by using Radiobuttons

Niklas Wünscherequested to merge
nwuensche/AuroraStore:onboarding-themes-checkbox-to-radiobuttons into master

It was possible to de-select all Themes in the Onboarding as Checkboxes where used. Now this is not possible anymore because we use Radiobuttons

Merge request reports