[wrt][xwalk-2793] Update one test and README

Impacted TCs num(approved): New 0, Update 1, Delete 0
Unit test Platform: Android
Android test result summary: Pass 1, Fail 0, Block 0
[wrt][xwalk-2715] Update 12 TCs to packertoolmanu

Impacted TCs num(approved): New 0, Update 12, Delete 0
Unit test Platform: Android
Android test result summary: Pass 12, Fail 0, Block 0
[wrt][XWALK-2652]Fix get uninstall info bug

[Detailed commit message (if have)]
Impacted TCs num(approved): New 0, update 1, deleted 0
Unit test platform: [tizen]
Test Result: Pass 1, Fail 0
Merge pull request #1106 from linshen/shenlin/fix-xwalk2279-1031

[wrt][XWALK-2652]Fix get uninstall info bug
Merge pull request #1102 from wanghongjuan/wanghongjuan/wrt/xwalk-2793

[wrt][xwalk-2793] Update one test and README
Merge pull request #1103 from wanghongjuan/wanghongjuan/wrt/xwalk-2715

[wrt][xwalk-2715] Update 12 TCs to packertoolmanu
[webapi] Improve tests purpose description for File Writer API
Merge pull request #1105 from kangxu/kangxu/webapi/tct-filewriterapi-w3c-tests/improve

[webapi] Improve tests purpose description for File Writer API