Fixed HTML5 and CSS3 syntax, removed HTML4 code and images/

I made fix to your web code.

Changes:
* **Moved from HTML to HTML5 syntax.** Example errors:
 * `<center>` isn't HTML5 tag, it's outdated. Better is making of `.center` CSS3 class and adding `text-align: center;` to that.
 * Any simple tag (like `<meta>`, without close-tag) need to have `/` at end (`<meta blahblah />`). Just `<script>` don't need that.
* Fixed CSS and added new classes.
* Renamed `stylesheets/` to `css/` and `javascripts/` to `js/`
* Removed `images/` because of it isn't used.
* Fixed `.gitignore` to be *gnulinux-friendly*.