[embedding][XWALK-1052] Leverage developer's sample tests for extension.

- Add extension support for embedding API.

Impacted tests(designed|approved): new 1, update 0, delete 0
Unit test platform: [Android]
Unit test result summary: pass 1, fail 0, block 0
[usecase-webapi] Fix the bug that the 'Pass' button is disabled when click the 'Cancle CSS FullScreen' button.

Impacted tests(approved): New 0, Update 1, Delete 0
Unit test platform: [TIZEN IVI]
Unit test result summary: Pass 1, Fail 0, Block 0
[embedding][XWALK-1052] Add one line to import Method class

Impacted tests(approved): new 0, update 1, delete 0
Unit test platform: [Android]
Unit test result summary: pass 72, fail 17, block 4
[webapi] Update the dir of 'How to build IAP extension'wiki

- Update the dir of 'How to build IAP extension'wiki
Merge pull request #727 from yunxliu/yunxliu/webapi/modify_iap

[webapi] Update the dir of 'How to build IAP extension'wiki
Merge pull request #720 from zhuyongyong/yongzhu/embeddingAPI/improve

[embedding][XWALK-1052] Add one line to import Method class
Merge pull request #691 from zhuyongyong/yongzhu/embeddingAPI-sample/add

[embedding][XWALK-1052] Leverage developer's sample tests for extension.
Merge pull request #687 from minxhuang/hm/misc/usecase-w3c/FullScreen

[usecase-webapi] Fix the bug that the 'Pass' button is disabled when click the 'Cancle CSS FullScreen' button.
[DeviceCapabilites] Fix wrong case.
Merge pull request #728 from legendlee1314/fixbug

[DeviceCapabilites] Fix wrong case.