Add `--version` flag

[miguelaeh]

Signed-off-by: Miguel A. Cabrera Minagorri mcabrera@vmware.com

Description of the change

Benefits

Add support for a --version flag to check the tool version

Possible drawbacks

Applicable issues

• fixes #26

Additional information

Checklist

• [x] Version bumped in package.json and package-lock.json according to semver.
• [x] New features are documented in the README.md
• [x] New features contain a new test at the tests folder
• [x] All tests pass running npm test