Exposes Context and Request on NancyRazorViewBase<T>

Makes it easier to access request and context data from a Razor view.
The Request property is just a shorthand version of Context.Request
and was added for convenience sake. Make it possible to use @Request
in your views
Merge pull request #1633 from thecodejunkie/razor-viewbase-pimping

Exposes Context and Request on NancyRazorViewBase<T>