[usecase-webapi][XWALK-1330]Add usecase for audiosystem

- Fail Reason: the error callback is invoked

Impacted TCs num(approved): New 1, Update 0, Delete 0
Unit test Platform: [Tizen-IVI]
Test result summary: Pass 0, Fail 1, Blocked 0
Merge pull request #513 from JianfengXu/xujf/usecase/audiosystem

[usecase-webapi][XWALK-1330]Add usecase for audiosystem