FormattingUtilities support for parsing dates in RFC 850 long year format

[TKharaishvili]

Addresses #187

[dougbu]

Looks great @TKharaishvili. Just needs another entry in the following test data:

AspNetWebStack/test/System.Net.Http.Formatting.Test/FormattingUtilitiesTests.cs

Lines 86 to 114 in 7493846

	public static TheoryDataSet<string, DateTimeOffset> ValidDateValues
	{
	get
	{
	return new TheoryDataSet<string, DateTimeOffset>
	{
	// RFC1123 date/time value
	{ "Sun, 06 Nov 1994 08:49:37 GMT", new DateTimeOffset(1994, 11, 6, 8, 49, 37, TimeSpan.Zero) },
	{ "Sun, 06 Nov 1994 08:49:37", new DateTimeOffset(1994, 11, 6, 8, 49, 37, TimeSpan.Zero) },
	{ "6 Nov 1994 8:49:37 GMT", new DateTimeOffset(1994, 11, 6, 8, 49, 37, TimeSpan.Zero) },
	{ "6 Nov 1994 8:49:37", new DateTimeOffset(1994, 11, 6, 8, 49, 37, TimeSpan.Zero) },
	{ "Sun, 06 Nov 94 08:49:37", new DateTimeOffset(1994, 11, 6, 8, 49, 37, TimeSpan.Zero) },
	{ "6 Nov 94 8:49:37", new DateTimeOffset(1994, 11, 6, 8, 49, 37, TimeSpan.Zero) },
	// RFC850 date/time value
	{ "Sunday, 06-Nov-94 08:49:37 GMT", new DateTimeOffset(1994, 11, 6, 8, 49, 37, TimeSpan.Zero) },
	{ "Sunday, 6-Nov-94 8:49:37", new DateTimeOffset(1994, 11, 6, 8, 49, 37, TimeSpan.Zero) },
	// ANSI C's asctime() format
	{ "Sun Nov 06 08:49:37 1994", new DateTimeOffset(1994, 11, 6, 8, 49, 37, TimeSpan.Zero) },
	{ "Sun Nov 6 8:49:37 1994", new DateTimeOffset(1994, 11, 6, 8, 49, 37, TimeSpan.Zero) },
	// RFC5322 date/time
	{ "Sat, 08 Nov 1997 09:55:06 -0600", new DateTimeOffset(1997, 11, 8, 9, 55, 6, new TimeSpan(-6, 0, 0)) },
	{ "8 Nov 1997 9:55:6", new DateTimeOffset(1997, 11, 8, 9, 55, 6, TimeSpan.Zero) },
	{ "Sat, 8 Nov 1997 9:55:6 +0200", new DateTimeOffset(1997, 11, 8, 9, 55, 6, new TimeSpan(2, 0, 0)) },
	};
	}
	}

[dnfclas]

All CLA requirements met.

[TKharaishvili]

@dougbu added the change you requested. Thanks for the guidance.

[dougbu]

Thanks very much @TKharaishvili. I'll get this in tomorrow…