* Added supported for close comment. After a review request is marked "submitted" or "discarded", submitter can add text to describe the submission.
* Fixed a bug that submitting review request will trash unpublished draft. Now, a confirm windows will popup to remind users.
* Showed submission date for submitted review request under summary.

TODO:
* Maybe rbtools support is needed.

Manually tested and unit tested.

The unit test output attached. Some failed and errors happened, but it looks like caused by windows environment. In fact, the output is the same before and after this commit.