[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