Security Bot

This adds [metascan configuration](https://liveramp.atlassian.net/wiki/spaces/CI/pages/1435664897/metascan) ([metascan.hcl](https://github.com/LiveRamp/bob/blob/master/metascan/README.md#metascanhcl)) to the repo. This PR was created by a bot. If this bot turns evil, let @bobisme know (bob on slack, #dev-product-security). [skip-ci]