Simplify Article

I fixed the sample application and made it more in-line with the types of samples we provide in our training labs.

I reduced the code in the sample application to the very basics to avoid confusion, and show the simplicity of using XAP.NET as the session state provider.

I removed redundant information for the article, and tried to avoid describing information that doesn't directly relate to XAP.NET and how it can be applied in an ASP.NET website.

Hopefully I didn't diverge from the original intention of the article or make incorrect assumptions about common knowledge of the various components.