[usecase-webapi][XWALK-2270] Fix bug for MediaRenderer

- Add Precondition for the test
- Failure analysis: Cannot play video

Impacted tests(approved): new 0, update 1, delete 0
Unit test platform: [Tizen IVI]
Unit test result summary: pass 0, fail 1, block 0
[webapi] Fix interface name for WebRTC

- Fix interface name
- Failure analysis: The ondatachannel event, onidpvalidationerror event and onidentityresult event cannot be fired. The Identity API extends the RTCPeerConnection interface is not support.

Impacted tests(approved): new 0, update 143, delete 0
Unit test platform: [Tizen IVI]
Unit test result summary: pass 111, fail 15, block 17
[webapi] Update 44 TCs for MediaRenderer

- Update 44 TCs for MediaRenderer
- Failure analysis: The statuschanged event and rendererlost event cannot be fired

Impacted tests(approved): new 0, update 44, delete 0
Unit test platform: [Tizen IVI]
Unit test result summary: pass 34, fail 4, block 6
[wrt][XWALK-2029]Update DB name

Detailed commit message (if have)]
Impacted TCs num(approved): New 0, update 4, deleted 0
Unit test platform: [tizen]
Unit test result summary: Pass 4 , Fail 0, Blocked 0

wrt-manifest-tizen-tests: PASS 390,Fail 0
[usecase-webapi]Update usecase for gamepad

- Use sample app from https://github.com/InternetExplorer/Gamepad-Sample to replace the existing usecase.
- Fail Reason: the gamepad can not connect to the android device, but this sample is passed in chrome 37.

Impacted TCs num: New 0, Update 1, Delete 0
Unit test Platform: Andriod
Unit test result summary: Pass 0, Fail 1, Blocked 0
[misc-cordova][xwalk-2289] Update cordova usecase description
Merge pull request #688 from linshen/shenlin/wrt/sqlite3

[wrt][XWALK-2029]Update DB name
Merge pull request #674 from wanghongjuan/wanghongjuan/misc/cordova-fix

[misc-cordova][xwalk-2289] Update cordova usecase description
Merge pull request #698 from JianfengXu/xujf/gamepad/usecase/update

[usecase-webapi]Update usecase for gamepad
Merge pull request #680 from yunxliu/yunxliu/webapi/webrtc_modify

[webapi] Fix interface name for WebRTC
Merge pull request #683 from yunxliu/yunxliu/misc/mediaRenderer_modify

[usecase-webapi][XWALK-2270] Fix bug for MediaRenderer
Merge pull request #684 from yunxliu/yunxliu/webapi/mediaRenderer_update

[webapi] Update 44 TCs for MediaRenderer