Add prototype about page.

Add:
        templates/index.html, static/(sass/about.sass, js/about.js, img/about/)
                -Add first iteration of the about page, with basic parallax
                scrolling and filler text.
Clean up style rules, improve positioning.

Add:
        static/sass/about.sass
                -Clean up existing style rules.
                -Add rules for the about sections' text.

        templates/about.html
                -Integrate with `templates/layout.html`, the project's global
                HTML template.
Update footer, minor changes to /about styling.

Add:
        static/sass/main.sass
                -Rework the footer, which is now fixed at the bottom of the
                screen as opposed to floored to the bottom of the page.
                Positioning at the bottom of the page doesn't make any sense
                with a technically infinite results page.
Finalize about page parallax styling.

Add:
        templates/about.html, static/js/about.js
                -Add a `speed` attribute to all image divs, which is used to
                determine the rate at which an image moves upward.

        static/img/about/bg2.png
                -Change image to another source-code screenshot.
Add text to about page; fix copyright year.

Add:
        templates/about.html, static/sass/about.sass
                -Add text to the about page, and the necessary styling for it.

        app.py, templates/layout.html
                -Add an automated copyright year loader.
Add some documentation, clean up before merge.

Add:
        static/js/about.js, static/sass/(index, about).sass
                -Minor cleanup before merge into `develop`: remove a superfluous
                style rule, update header comments.
Merge branch 'feature/style' into develop

Add a styled and mostly content-complete about page.