Changes to improve the layout and responsiveness of the landing page & updates page.

Changes to Landing page include

- Added registration button
- mobile friendly menu collapse
- container now stretches 100% across smaller screens as per original design
- Updates to landing page text and main nav text and icons
- Improved scaling of logo across different screen sizes.

Updates page

- improved updates feed for mobile devices (480px)
- Improved disaster card styling to avoid it stretching

& other small changes as required.