v2.0.0 Use command-line-parser 3.0

• 6cd4ff3 Fix command-line-options-test
• 943e9df Merge pull request #146 from cgay/new-cli
• 87d6aef Update for recent command-line-parser changes

Commit 87d6aef also changed the way Testworks accepts "options" on the command line, moving it from being positional args to a flag named --options, hence the major version bump.