Allow to select where to store the db file

I can run the program from an USB drive so I can use it on windows /linux machine (in wine) but the db file is stored on the hard drive with all the list information. On windows 7, it's at C:\Users\\AppData\Local\PomodoroApp and on Ubuntu 12.04, it's at home/mj/.wine/dosdevices/c:/users//Local Settings/Application Data/PomodoroApp. There should be a way to select its location.