Option to ignore some files

I'd like to ignore some files by either using some option like `--ignore` or being able to pass the entire glob pattern to the CLI.

The latter seems to not be possible because of this `path.join(inputDir, '!(index).{js,ts}')`.
https://github.com/Andarist/cherry-pick/blob/c78c2a3d2862e3650ce83021c16e3bc07155df28/lib/index.js#L27

I think it would be better if the library let the user have full control over the glob pattern.

Related to https://github.com/reakit/reakit/issues/106