Combine javascript files.

Now the main page doesn't include any JS since it doesn't use them. This results in -4 http requests and a lot of bytes saved.
Merge pull request #151 from XhmikosR/combine-js

Combine javascript files.
Rename folders to the shorter and more standard "img" and "js".
Use a CSS sprite for the homepage images.

-2 http requests, -0.5KB.