Write and validate .NET specifications in BDD style.
This framework can be used along with any other unit testing, mocking frameworks.
Main purpose of this framework is to allow writing unit tests in BDD style (similar to RSpec)
Simple usage example:
```
using System;
using NUnit.Framework;
namespace Demo.Spec
{
public class CreditCardTest : ArtSpec.Spec
{
/* note: override this method to define specification */
protected override void Specify()
{
Console.WriteLine(@"CreditCardTest demonstrates using NUnit framework");
It("should have a valid month", () =>
{
/* note: defines expectation of an exception */
Error
(delegate { new CreditCard {Month = 0}; });
Error(delegate { new CreditCard {Month = 13}; });
Error(delegate { new 
