Refactoring Northwind and OptimisticConcurrency functional tests
Split Northwind model into separate files and added a context class
Avoiding sharing any state between the contexts that mutate the model or the data
Renamed provider-specific test classes to include the provider name
Cleaning leftover databases
tests for issue 963 - disabled for now, until the big is fixed
Remove NotNull from overriding members
Fix #717 - Boolean expression bug

Added support for unary boolean expression translation to relational.
Adding descriptions for NuGet packages
Merge branch 'release' into dev
Normalize line endings