Added support for @Html.Raw(...) to match standard Razor "raw" syntax.

A 'Fake' Html class mimicking the standard Razor syntax of @Html.Raw(...). 
- Code is the same as the Raw method that is in TemplateBase.
- I'm just looking to get back to the standard Razor syntax of @Html.Raw(...) rather than using just @Raw(...) which will give us the ability to save our templates as .cshtml and get all the syntax highlighting etc from Visual Studio.
- As per comments here: http://stackoverflow.com/questions/9661180/how-do-i-output-raw-html-when-using-razorengine-not-from-mvc.