METRON-1580 Release candidate check script requires Bro Plugin

[nickwallen]

Not all Metron releases will include a new version of the Bro Plugin. The release candidate script currently requires it though. These changes make the --bro argument option which allows us to validate releases which do not contain an updated Bro plugin.

Testing

./dev-utilities/release-utils/metron-rc-check --version=0.5.0 --candidate=RC1

Pull Request Checklist

• Is there a JIRA ticket associated with this PR? If not one needs to be created at Metron Jira.
• Does your PR title start with METRON-XXXX where XXXX is the JIRA number you are trying to resolve? Pay particular attention to the hyphen "-" character.
• Has your PR been rebased against the latest commit within the target branch (typically master)?
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• Have you included steps or a guide to how the change may be verified and tested manually?
• Have you ensured that the full suite of tests and checks have been executed in the root metron folder via:
• Have you written or updated unit tests and or integration tests to verify your changes?
• If adding new dependencies to the code, are these dependencies licensed in a way that is compatible for inclusion under ASF 2.0?
• Have you verified the basic functionality of the build by building and running locally with Vagrant full-dev environment or the equivalent?

[ottobackwards]

+1 by inspection, thanks @nickwallen