[misc-usecase][XWALK-1071] Add a TC for filesystem tizen

- Add a filesystem TC for createfile and readfile
- Failure analysis: https://crosswalk-project.org/jira/browse/XWALK-1827

Impacted tests(approved): new 1, update 0, delete 0
Unit test platform: [Tizen IVI]
Unit test result summary: pass 0, fail 1, block 0
Merge pull request #286 from yunxliu/yunxliu/misc/filesystem

[misc-usecase][XWALK-1071] Add a test for Tizen File System API