Number of vulnerabilities as exit status code

Hi,

How do you feel about including an option for returning exit status other than 0 when vulnerabilities are found? (We implemented it so it returns the number of vulnerabilities.) We need this to include down in our deployment pipeline.

I named the option with respect to Brakeman's name, since we use is as additional security measurement. I can rename it, though, if you think it could be improved. 

Thanks.