Add search-engine files, a favicon, and 404 page. Close #70, #71.

Add:
        app.py, templates/error404.html, static/sass/error404.sass
                -Add Flask 404 handler and styled 404 page.

Add:
        app.py
                -Remove hard-coded routes for files in the application's "root"
                (`static/`) directory; redefined Flask's `static_url_path`
                accordingly. Files can now be directly accessed by URL.

        bitshift/assets.py
                -Remove the `static/` prepended to all resource paths.

Add:
        static/js/main.js
                -Add a global javascript file, with bitshift's Google Analytics
                snippet.

        static/google10335120a3066831.html
                -Add our Google "Administrator Console" authentication.

Add:
        static/img/favicon.ico
                -Add a favicon.

        static/(robots.txt, sitemap.xml)
                -Add search-engine files. `bitshift` is not yet registered with
                Google.

Add a styled and mostly content-complete about page.

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

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:
        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.

Conflicts:
	bitshift/crawler/crawl.py
	bitshift/languages.py

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.

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.

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.

New commits in `feature/style` address various issues.