Removed superfluous outer container from body in base.html, and replaced the...

Removed superfluous outer container from body in base.html, and replaced the <div>s used for the header, content and footer with their HTML5 semantic counterparts: <header>, <main>, and <footer>.

Gave the top navigation bar a _massive_ overhaul, making extensive use of CSS3's flex properties.

Modified the behaviour of the body and its top level header, main and footer to behave responsively, and tested this on various sized viewports.

Revamped the easter egg ;)

Admin page is royally broken, so this will be the next thing for me to fix.