CSS and HTML Fixes

HTML
- Fixed header absolute links for og:image & image_src
- Fixed h3 on sect2_aboutbody
- Made one footer with 2 section instead of 1 section and a footer
(this fixes the big padding of the former last section)
- Removed uneeded comment about tuktuk.min.js

CSS
- Moved #clear and #clear2 to custom.min.css (Please do not edit
tuktuk.min.css since it's the framework and if we update it we will
lose your edit, use custom.min.css instead.)
- Fixed top left logo alignment on mobile device (now perfectly
centered.)