v0.5.4

• 8a36c4b Fix issue with react-router <Link />
• 80e5456 Fix Modal to stop calling onRequestClose when the modal is already closed.
• a26ee48 Add Step Breadcrumbs.
• 8e94a83 Improve input messages styling.
• b75f4c1 Replace Modal's render method (render to unstable_renderSubtreeIntroContainer).