[usecase-webapi] Improve NBS usecase.

- Fix the bug that nothing happen after click "Request" button.
- Draw a message frame to show NBS messages above the buttons.

Impacted tests(approved): New 0, Update 1, Delete 0
Unit test platform: [Tizen IVI]
Unit test result summary: Pass 1, Fail 0, Block 0
Merge pull request #516 from minxhuang/hm/misc/usecase-tizen/NBS-hotfix

[usecase-webapi] Improve NBS usecase.