v5.0-alpha

Add dependency for version 2.5.6 of Trackable Entities.

• Change IObjectState to ITrackable
• Change ObjectState to TrackingState
• Add DbContext.ApplyChanges to SyncObjectState
• Update Json.Net packages to 10.0.3
• Prefix assembly names with Urf.

https://www.nuget.org/packages?q=urf