Pick a static analysis tool, shellcheck, and write the plugin.

Shellcheck is a static analysis tool, like pep8, that can automatically detect problem with sh/bash script and commands. 

The feature of the shellcheck plugin will let ReviewBot can prove feedback for sh/bash script. Right now, reviewboard can detect problem with sh/bash script, if sh/bash is included in a new review request.

Test shellcheck plugin:

    1). Create a Reviewbot user, that it will review sh/bash script.

    2). Make own repository, add it to RB, and add a .reviewboardrc with a REVIEWBOARD_URL pointing to localhost.

    3). Set reviewboard extention so that reviewbot tool shellcheck will run aotumatically when there is a new review request with sh/bash script.

    4). Create a review request on local instance of Review Board with sh/bash script. Once the ReviewBot user make a review of the code, compare the result with running shellcheck in terminal on the same sh/bask script. If all the outputs are same, shellcheck will works fine.

    5). After all above test are correct. Test explicitly exclude the specified codes from the report. Compare with the original shellcheck in terminal, and see if all the output are correct.
Run unit tests on reviewboard, see if the new plugin break any other features of reviewboard.