Fixed code to apply new standards

I made fix to your web code.

Changes:
* **Moved from HTML4 to HTML5 syntax.**
* 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*.