[demo-express] Merge 4 tests to demo express from usecase

- Merge Download, SystemInfo, SystemSettingIncomingCall and SystemSettingScreen to demo from usecase
- Download: Download folder default as N/A
- SystemSetting IncomingCall: No audio file default as N/A, click button adding error note
- SyttemSeting Screen: No picture file default as N/A, click button adding error note
Merge pull request #11 from xinliux/xinliux/merge-from-usecase

[demo-express] Merge 4 tests to demo express from usecase