Update TLS Observatory Parser Linting: Cert Lint into TLS Observatory

[jcjones]

Similar but different to #187, this is to integrate the AWS Labs Cert Lint tool's output into the certificate parser's output.

The integration is expected to be via a shell execution of the other utility. If we need to do something more exotic (RPC to a Docker instance, for example), that should be a follow-up. For now, this issue should assume we can call out to the executable and read the results from stdout.

[adamdecaf]

I'd be open to trying this. Would tls-observatory need to worry about cloning and installing certlint?

Would this be in a new worker? (Either one worker per cert lint tool or all tools under one worker.)

[jvehent]

I think this would be a new worker, probably similar to evChecker that also executes a separate binary. The docker image will need to retrieve and build certlint as part of the travisci run.