Added DictionaryConverter

This converter, which is not used by default (not in DefaultContractResolver), converts JSON to Dictionary<string, object> recursively. So any JSON dictionary gets converted to Dictionary<string, object>, and any JSON array to object[].

Such dictionary fulfills popular demand to deserialize JSON to simple dictionary/array, for example requested at http://stackoverflow.com/questions/1207731/how-can-i-deserialize-json-to-a-simple-dictionarystring-string-in-asp-net/23867458