fix to issue 788 - Tracking entities has a discrepancy in behavior between sync and async. For sync, objects returned to the customer have the same reference as ones created and stored in state manager. For async, we do create and store objects in state manager, but return the original ones to the customer. This could cause errors for some scenarios (issue 788) - we would end up with same entity being tracked twice which then would lead to a validation error. CR: Andrew
Reacting to CLR package versioning changes
Adding ConfigurationSource to track where the model changes came from.
Adding ability to ignore entity types to InternalModelBuilder.
Simplifying filtering in ApiConsistencyTest

Fixes #802
Making the Model API more consitent with EntityType
Adding ConfigurationSource parameters to InternalEntityBuilder.
Random sequential access...

Add SQL Server-specific model APIs for sequences and clustering

This adds SQL Server-specific fluent and core metadata APIs as discussed in the design meeting here: https://github.com/aspnet/EntityFramework/wiki/Design-Meeting-Notes---October-2,-2014

The sequence APIs are different from discussed in the meeting because they now more explicitly separate the use of sequences for value generation from the definition of sequences in the relational model. The definition of sequences now has a relational-specific fluent API and this is the only place where characteristics of the sequence can be changed. The model can then be setup to use sequences for value generation, as can each property.

This code doesn't include connecting up the new annotations to the Migrations code.