Modified application to use SQLite db
 - Web.config and nuget packages revamped.
 - Model classes now use 64-bit artificial keys
Modified solution in preparation for integration and functional testing.
 - Renamed CountDownTests to CountDownUnitTests
 - Added prefix to all unit test categories
 - Added CountDownIntegrationTests, CountDownFunctionalTests projects
ToDoController
 - Added constructor for IToDoItemRepository
 - Cleaned up code in Edit action

UserRepository, ToDoItemRepository
 - Removed unneeded constructors
Removed LoginAttempt, User, and ToDoItem classes from controller tests. Changes include...
 - Properties in domain classes are now virtual
 - ToDoControllerTests, UserControllerTests use mocks
 - Authentication tests in UserController improved