Allow CLI exclusion of a single test

[brian-rickman]

Current CLI syntax allows excluding a group of tests via -x, but I sometimes need to exclude a single test, and would like to do this without creating a new group for it or adding it to the quarantine group. I would like for the CLI to support a command similar to this:

-x quarantine,com.facebook.presto.tests.hive.TestExternalHiveTable -g hive_connector