Create lib/ structure, clean up js.

Add:
    static/(css, js)/lib
        -Add directories to contain third-party library files (eg,
        `jquery.min.js`).

    templates/index.html, static/js/index.js
        -Move `typeahead` initialization from `index.html` to `index.js`.

    static/sass/index.sass
        -Refactor `twitter-typeahead` specifier hierarchy.