Workflow issue with getting started content and upgrading Brackets

[njx]

1. Clean prefs.
2. Install Brackets Sprint 13 and launch it. You'll see the getting started content that we ship with Sprint 13. (In the current installer we're still showing the Brackets source code, but the getting started content will have the same issue once we roll that into the real installer.)
3. Install Brackets Sprint 14 and launch it. Since this is no longer the first launch (and we don't delete or switch prefs when upgrading), we just pull your current project from prefs, so you'll still see the getting started content from Sprint 13. (Arguably this is a problem in itself.)
4. Uninstall Brackets Sprint 13. This deletes the Sprint 13 getting started content.
5. Relaunch Brackets Sprint 14. You get an error saying that the project no longer exists. Since we fall back to the default project when we can't open a project, we'll now open the Sprint 14 getting started content.

This might not be the most common scenario, since in between using Sprint 13 and Sprint 14, the user will probably open some other project of their own, and so when they run Sprint 14, they'll just see that project. However, in that case, the old getting started content from Sprint 13 will still be in the "recent projects" dropdown. If the user tries to select it, they'll experience the same behavior as step (4), so they'll eventually get the right content, but after getting an error dialog.

(Additionally, if they don't uninstall sprint 13, then they'll keep seeing the old getting started content without realizing it.)

[njx]

Moving to sprint 15.

[pthiess]

Reviewed - assigned to @njx, moved to sprint 14.

[njx]

Working on a simpler fix.

[njx]

Fixed. Note that this doesn't deal with the upgrade from Sprint 13 to 14--we'll just have to release note that.