Make XUnit tests dynamically skippable for SpecLight

SpecAttribute.cs

	/// <summary>
	/// Speclight users like to see "Pending" steps (that throw NotImplementedException) as "skip" not "fail"
	/// </summary>
	public class SpecAttribute : FactAttribute
	{
		protected override IEnumerable<ITestCommand> EnumerateTestCommands(IMethodInfo method)
		{
			yield return new SkipIfNotImplemented(method);
		}

		class SkipIfNotImplemented : FactCommand
		{
			public SkipIfNotImplemented(IMethodInfo method) : base(method){}

			public override MethodResult Execute(object testClass)
			{
				try
				{
					return base.Execute(testClass);
				}
				catch (NotImplementedException e)
				{
					return new SkipResult(testMethod, DisplayName, e.Message);
				}
			}
		}

		//the rest of this file can be deleted if you're not using ApprovalTests.Net

		static SpecAttribute()
		{
			ApprovalTests.Namers.StackTraceParsers.StackTraceParser.AddParser(new StackTraceParser());
		}

		public class StackTraceParser : AttributeStackTraceParser
		{
			public override string ForTestingFramework
			{
				get { return "xUnit Spec"; }
			}

			protected override string GetAttributeType()
			{
				return typeof(SpecAttribute).FullName;
			}
		}

		
	}