Added TimeSpan handling for XML incl. UnitTest

Format is ISO_8601 for durations (XmlSerializer uses this by default)
More info: http://en.wikipedia.org/wiki/ISO_8601#Durations

Author: ntziolis

RestSharp.Tests/XmlTests.cs

@@ -254,6 +254,48 @@ public void Can_Deserialize_Elements_to_Nullable_Values()
 			Assert.Equal(new Guid(GuidString), output.UniqueId);
 		}
 
+        [Fact]
+        public void Can_Deserialize_TimeSpan()
+        {
+            var culture = CultureInfo.InvariantCulture;
+            var doc = new XDocument(culture);
+
+            TimeSpan? nullTimespan = null;
+            TimeSpan? nullValueTimeSpan = new TimeSpan(21, 30, 7);
+
+            var root = new XElement("Person");
+            root.Add(new XElement("Tick", new TimeSpan(468006)));
+            root.Add(new XElement("Millisecond", new TimeSpan(0, 0, 0, 0, 125)));
+            root.Add(new XElement("Second", new TimeSpan(0, 0, 8)));
+            root.Add(new XElement("Minute", new TimeSpan(0, 55, 2)));
+            root.Add(new XElement("Hour", new TimeSpan(21, 30, 7)));
+            root.Add(new XElement("NullableWithoutValue", nullTimespan));
+            root.Add(new XElement("NullableWithValue", nullValueTimeSpan));
+
+            doc.Add(root);
+
+            var xml = new XmlDeserializer
+            {
+                Culture = culture,
+            };
+
+            var response = new RestResponse { Content = doc.ToString() };
+
+            var d = new XmlDeserializer()
+            {
+                Culture = culture,
+            };
+            var payload = d.Deserialize<TimeSpanTestStructure>(response);
+            Assert.Equal(new TimeSpan(468006), payload.Tick);
+            Assert.Equal(new TimeSpan(0, 0, 0, 0, 125), payload.Millisecond);
+            Assert.Equal(new TimeSpan(0, 0, 8), payload.Second);
+            Assert.Equal(new TimeSpan(0, 55, 2), payload.Minute);
+            Assert.Equal(new TimeSpan(21, 30, 7), payload.Hour);
+            Assert.Null(payload.NullableWithoutValue);
+            Assert.NotNull(payload.NullableWithValue);
+            Assert.Equal(new TimeSpan(21, 30, 7), payload.NullableWithValue.Value);
+        }
+
 		[Fact]
 		public void Can_Deserialize_Custom_Formatted_Date()
 		{

RestSharp/Deserializers/XmlDeserializer.cs

@@ -179,7 +179,12 @@ private void Map(object x, XElement root)
 					var raw = value.ToString();
 					value = string.IsNullOrEmpty(raw) ? Guid.Empty : new Guid(value.ToString());
 					prop.SetValue(x, value, null);
-				}
+                }
+                else if (type == typeof(TimeSpan))
+                {
+                    var timeSpan = XmlConvert.ToTimeSpan(value.ToString());
+                    prop.SetValue(x, timeSpan, null);
+                }
 				else if (type.IsGenericType)
 				{
 					var t = type.GetGenericArguments()[0];