Bug fixes

- The Settings app-based settings (logout, change login host) were not working when the app was first launched.

- There are race conditions on `SFRootViewManager` which can cause the login view not to be displayed when the app is launched.
Force setting `SFRootViewManager`'s main window up front, to make sure it's getting the just-configured `UIWindow`.  Also, `[UIApplication sharedApplication].windows[0]` should pretty much always be the "main" (original) window in all sane use cases.