Fixed the Attributed Tests

AttributedPropertyTests (29 tests), Success

Refactored the CustomSerializer<T> constructor to verify serialization.

Might want to consider different tests (like testing the inner exception) since the reflection for

`serializer = (IXmlSerializer)Activator.CreateInstance(typeof(CustomSerializer<>).MakeGenericType(type), defaultNamespace, extraTypes, rootElementName);`

Will mask the exception as it should.