[usecase-webapi] Merge tizen and w3c to usecase

- Merge webapi-usecase-tizen-tests and webapi-usecase-w3c-tests to webapi-usecase-tests
- Test platform: Tizen IVI and Android, app can run well on these two platform
Merge pull request #776 from xinliux/xinliux/usecase/MergeTizen

[usecase-webapi] Merge tizen and w3c to usecase