Change file descriptor to stderr if status is greater than 0 about bash_shell_mock

[ckstettler]

The bats 'run' command redirects stdout and stderr so in that case it would not be helpful in the test. However what could make sense is to add a --stderr option so that the user can control what goes to stderr vs stdout rather than the script deciding. We would also need a means of capturing the output for validation purposes.

[tyleroconnell]

Due to a lack of executive sponorship at Capital One, this project is being archived. All outstanding pull requests and issues will be closed and ownership of this project will be moved to @ckstettler's fork.