[misc] Add a usecase for content

- Fail reason: when input different parameter of directoryId, the content.find() method return same file list.
- Fail reason: when delete file on the device, content.find() also return the old file list.

Impacted TCs num(approved): New 1, Update 0, Delete 0
Unit test Platform: [Tizen IVI]
Test result summary: Pass 0, Fail 1, Blocked 0
Merge pull request #319 from JianfengXu/xujf/misc/content

[misc] Add a usecase for content