fix bug when importing a sycned list

If you attempt to set up a synced list into a non-home directory that
does not have a .todos.json file, it would overwrite the .todos.json in
the home directory.

The fix was to initialize the FileStore repo, so it creates a
.todos.json locally first.

ultralist/app.go

@@ -352,7 +352,8 @@ func (a *App) SetupSync() {
 			return
 		}
 	}
-	// pull a list from ultralist.io
+
+	// at this point, it is known that a local todos file does not exist.
 	type Response struct {
 		Todolists []TodoList `json:"todolists"`
 	}
@@ -373,6 +374,7 @@ func (a *App) SetupSync() {
 
 	idx, _, _ := prompt2.Run()
 	a.TodoList = &response.Todolists[idx]
+	a.TodoStore.Initialize()
 	a.TodoStore.Save(a.TodoList.Data)
 
 	a.EventLogger = NewEventLogger(a.TodoList, a.TodoStore)