[misc]Add fullscreen tcs for web-mbat-tests

[Detailed commit message (if have)]
Impacted TCs num(approved): New 1, update 0, deleted 0
Unit test platform: [tizen]
Unit test result summary:Pass 0, Fail 1,Block 0
BUGID:https://crosswalk-project.org/jira/browse/XWALK-2577
[wrt]update const.py path for wrt-manifest-tizen-tests

[Detailed commit message (if have)]
Impacted TCs num(approved): New 0, update 4, deleted 0
Unit test platform: [tizen]
Unit test result summary:Pass 0, Fail 2,Block 1
Test create folder ok,block/fail by:
https://crosswalk-project.org/jira/browse/XWALK-2290
Merge pull request #930 from linshen/shenlin/update-manifest0919

[wrt] [WEBQA-150] update const.py path for wrt-manifest-tizen-tests
Merge pull request #929 from linshen/shenlin/misc-update-0919

[misc]Add fullscreen tcs for web-mbat-tests
[webapi][xwalk-2561] Update codes based on Chromium implement

- mp4a.40.8/mp4v.20.8 is also not supported in chromium 38, need use mp4a.40.2/mp4a.40 instead.
- Verified on Crosswalk 9.38.204.0

Impacted tests(approved): new 0, update 2, delete 0
Unit test platform: [Tizen IVI][Android]
Unit test result summary: pass 2, fail 0, block 0
[wrt][XWALK-1668]Add new audiopolicy testcase

Impacted TCs num(approved): New audiopolicy 7, update multiuser 3, deleted 0
Implacted TCs num(designed): New 2, Update 0, deleted 0
Unit test platform: [tizen]
UT result: Pass:7, Fail 1, block 1
Fail: Crosswalk_AudioPolicy_WebappAudioPlay: two webapp audio can be play at the same time
Block:Crosswalk_AudioPolicy_Muliple_Sinks: No bluetooth headset
[doc] Transfer pdf to md in doc directory
Merge pull request #934 from kangxu/kangxu/wrt/doc/addMD

[doc] Transfer pdf to md in doc directory
Merge pull request #933 from haoxli/haoxli/webapi/xwalk-2561-video

[webapi][xwalk-2561] Update codes based on Chromium implement
Merge pull request #931 from linshen/shenlin/addaudioplicy

[wrt][XWALK-1668]Add new audiopolicy testcase
[wrt] Add subcase and type to tests.xml
[usecase-webapi] Demo for adding pluggable step info

Impacted TCs num(approve): New 0, Update 0, Delete 1
Unit test Platform: Andriod
Unit test result summary: Pass 0, Fail 0, Blocked 0
Merge pull request #896 from JianfengXu/xujf/usecase/step

[usecase-webapi] Demo for adding pluggable step info
Merge pull request #938 from wanghongjuan/wanghongjuan/wrt/subcase

[wrt] Add subcase and type to tests.xml
[wrt-usecase][xwalk-2394] Update TCs due to feature resolved

Impacted TCs num(approved): New 2, Update 4, Delete 0
Unit test Platform: Android
Android test result summary: Pass 6, Fail 0, Block 0
Merge pull request #943 from wanghongjuan/wanghongjuan/usecase/xwalk-2394

[wrt-usecase][xwalk-2394] Update TCs due to feature resolved