[webapi] Update xwalk-launcher to open_app

Impacted tests(approved): new 0, update 112, delete 0
Unit test platform: [Tizen IVI]
Unit test result summary: pass 112, fail 0, block 0
Merge pull request #1206 from yunxliu/yunxliu/webapi/modifyScript

[webapi] Update xwalk-launcher to open_app