[webapi] Merge webapi-dlna-ivi-tests to webapi-dlna-xwalk-tests

Impacted tests(approved): new 0, update 0, delete 0
Unit test platform: [Tizen IVI]
Unit test result summary: pass 37, fail 15, block 23
[webapi][XWALK-2104] update the variable name for auidosystem

- Fail Reason: the error callback is invoked.

Impacted TCs num: New 0, Update 1, Delete 0
Unit test Platform: [Tizen-IVI]
Test result summary: Pass 0, Fail 1, Blocked 0
Merge pull request #499 from yunxliu/yunxliu/webapi/merge_dlna

[webapi] Merge webapi-dlna-ivi-tests to webapi-dlna-xwalk-tests
Merge pull request #500 from JianfengXu/xujf/audiosystem/2104

[webapi][XWALK-2104] update the variable name for auidosystem