-Added .NET 4.5 version
-Added IReadOnlyCollection<T> and IReadOnlyDictionary<TKey, TValue> support
-Incremented version to 5.0
-Added BigInteger support
-Changed serialization callbacks on JsonContract to delegates
-Added Obsolete attributes to old serialization methods on JsonContract
-Added VS and ReSharper settings files
-Fixed converting null JSON value to XML
-Fixed tests