Make script urls relative to current index.php directory.

[johnnymast]

Referencing #28

Sample fix for index.php:

<script type="text/javascript" src="./js/dom.js"></script>
<script type="text/javascript" src="./js/websockets.js"></script>
<script type="text/javascript" src="./js/interface.js"></script>

or

<script type="text/javascript" src="js/dom.js"></script>
<script type="text/javascript" src="js/websockets.js"></script>
<script type="text/javascript" src="js/interface.js"></script>

[johnnymast]

This will fix #28