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.
Updating System.Text.RegularExpressions version
Reacting to CoreCLR version changes
Commands: Add functional tests