Corrected name of test.
Added set of EditViewModel tests.
Refactored initial let binding for file system back end.
Made INotesBackends disposable, as there's likely to be resources that need a timely clean up.
Added tests to test picking up changes from disk made outside of application.
Major redesign of API, changing responsibilities of INotesBackend and adding Store which handles the notes themselves. Still need to add logic to detect changes from disk to keep up to date.