Added a method to customize the JsonSerializerSettings

-The method CreateDefaultSerializerSettings was modified to private and
now it create a JsonSerializerSettings with the Culture of the current
Thread.

-The method SetCreateSerializerSettingsHandler was created to set a
handler to be called by the CreateSerializerSettings. If the handler was
not informed, the method CreateSerializerSettings will call the
CreateDefaultSerializerSettings.