Added support for Guid values

Liquid.NET.Tests/Utils/LiquidValueConverterTests.cs

@@ -123,6 +123,19 @@ public void It_Should_Covert_A_DateTime()
             Assert.That(val.Value, Is.EqualTo(new LiquidDate(dateTime)));
         }
 
+        [Test]
+        public void It_Should_Convert_Guid_To_LiquidString()
+        {
+            // Act
+            var testValue = new Guid();
+            var val = _converter.Convert(testValue);
+
+            // Assert
+            Assert.That(val.HasValue, Is.True);
+            Assert.That(val.Value, Is.TypeOf<LiquidString>());
+            Assert.That(val.Value, Is.EqualTo(LiquidString.Create(testValue.ToString("D"))));
+        }
+
         [Test]
         public void It_Should_Convert_Generic_List_To_Collection()
         {

Liquid.NET/src/Utils/LiquidValueConverter.cs

@@ -130,6 +130,12 @@ private Option<ILiquidValue> FromPrimitive(Object obj)
                 var val = obj as IDictionary;
                 return CreateHash(val);
             }
+
+            var guidVal = obj as Guid?;
+            if (guidVal.HasValue)
+            {
+                return LiquidString.Create(guidVal.Value.ToString("D"));
+            }
             return null;
         }