Integrate Jekyll

This PR adds Jekyll to `gh-pages` (basic configuration, instructions, layout). Navigation could be modeled like this at base layout:

```liquid
<div class="navi">
    <ul>
        <li {% if page.url == '/' %}class="selected"{% endif %}><a href="/">Home</a></li>
        <li {% if page.url == '/projects/' %}class="selected"{% endif %}><a href="/projects/">Projects</a></li>
        <li {% if page.url == '/professionals/' %}class="selected"{% endif %}><a href="/professionals/">Professionals</a></li>
    </ul>
</div>
```