Add universal app section and unicity of product across sections
Fix attribute param
Change music section titles to plural forms
Fix music album section
Remove product duplicates
Fix section title when some sections are empty
Change iPad/iPhone apps detection with screenshots instead of supported devices

supportedDevices is not a good way to recognize an iPhone only app, as it will most of the time be compatible with iPad devices.
iPadScreenshotUrls and screenshotUrls seem to be a better way.