New db4o demo for ADO.NET Data Services (aka Astoria)

The purpose of this demo is tho show you how the .NET version of db4o can fully act as a datasource via the ADO.NET Data Services framework. This is achieved by using db4o's LINQ provider while supporting the interfaces IQueryable and IUpdatable required by Astoria to operate on the database. IQueryable allows db4o to expose entities to the Data Services framework while IUpdatable allow CRUD operations over the datastore.