Use a small subset of Bootstrap to style the front page

Also includes a possible app icon (a flask) that is displayed on the homepage and used as a favicon (and all the other icon types)

It would be good to replace the existing glasses icon with this one when you next work on the frontend parts, @rh389. I had in my mind that Neptune was primarily white, which was apparently incorrect! I'll possibly see about updating a front page to make it match a bit better once you've changed from the classic theme.

Feel free to merge this if you're happy with the change.