[usecase-wrt] modify wrt-usecase-tizen-tests

[Detailed commit message]
Unit test platform: [tizen]
Unit test result summary: pack to wgt/xpk, all tcs is showing normally
[misc-xwalk]Move webaudio sample to xwalk system tests

- Fail Reason: the sample crashes, when repeatedly navigating to webpages with audio playback using WebAudio

Impacted TCs num(approved): New 0, Update 1, Delete 0
Unit test Platform: Andriod
Test result summary: Pass 0, Fail 1, Blocked 0
Merge pull request #524 from JianfengXu/xujf/misc/xwalk

[misc-xwalk] Move WebAudio sample to xwalk system tests
[wrt] Separate wrt-rtcore-android-tests into 3 suites
[wrt] Fix issue for wrt-extensionmanu-android-tests
[wrt] Fix issue for wrt-packagemgtmanu-android-tests
Merge pull request #533 from linshen/modify-wrt-usecase-tizen-test

[usecase-wrt] modify tizen usecase for wrt-usecase-tizen-tests
Merge pull request #534 from kangxu/kangxu/wrt/wrt-rtcore-android-tests/separate

[wrt] Separate wrt-rtcore-android-tests into 3 suites
Merge pull request #535 from kangxu/kangxu/wrt/wrt-extensionmanu-android-tests/fix

[wrt] Fix issue for wrt-extensionmanu-android-tests
Merge pull request #536 from kangxu/kangxu/wrt/wrt-packagemgtmanu-android-tests/fix

[wrt] Fix issue for wrt-packagemgtmanu-android-tests