Added about section to dashboard

Because of infinite scrolling on main page, it's a bit difficult to access the
version in the footer, so it's been added to the dashboard.
Loading spinner and debounced scroll handler
Menu animation and layout fix
Do not break if zipballs directory is missing
Improved load timing for infinite scroll
Fxied rapid scroll bug
Better contrast with content list
Make disk space bar darker
Animated scroll-to-top
Styling for end-of-archive cue