Internalize ProductHeaderValue

What Haacked, PaulBetts, and Shiftkey suggested

Octokit/Http/ProductHeaderValue.cs

@@ -0,0 +1,70 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace Octokit
+{
+    public class ProductHeaderValue
+    {
+        ProductHeaderValue()
+        {
+
+        }
+
+        public ProductHeaderValue(string name)
+        {
+            _productHeaderValue = new System.Net.Http.Headers.ProductHeaderValue(name);
+
+        }
+
+        public ProductHeaderValue(string name, string value)
+        {
+            _productHeaderValue = new System.Net.Http.Headers.ProductHeaderValue(name, value);
+        }
+
+        System.Net.Http.Headers.ProductHeaderValue _productHeaderValue;
+
+
+        public string Name
+        {
+            get { return _productHeaderValue.Name; }
+        }
+
+        public string Version
+        {
+            get { return _productHeaderValue.Version; }
+        }
+
+        public override bool Equals(object obj)
+        {
+            return _productHeaderValue.Equals(obj);
+        }
+
+        public override int GetHashCode()
+        {
+            return _productHeaderValue.GetHashCode();
+        }
+
+        public override string ToString()
+        {
+            return _productHeaderValue.ToString();
+        }
+
+        public static ProductHeaderValue Parse(string input)
+        {
+            return new ProductHeaderValue { _productHeaderValue = System.Net.Http.Headers.ProductHeaderValue.Parse(input) };
+        }
+
+        public static bool TryParse(string input,
+            out ProductHeaderValue parsedValue)
+        {
+            System.Net.Http.Headers.ProductHeaderValue value;
+            var result = System.Net.Http.Headers.ProductHeaderValue.TryParse(input, out value);
+            parsedValue = result ? Parse(input) : null;
+            return result;
+
+        }
+    }
+}