Add retrieving list of versions support

[tagirahmad]

What is the purpose of this pull request?

Add retrieving list of versions support

What changes did you make? (overview)

Added #logidze_versions method which retrieves list of versions of model depending on options provided (reverse and include_self

If reverse is provided, reversed Enumerator will be returned.

If include_self is provided, the list will contain also current version of the model.

Is there anything you'd like reviewers to focus on?

Checklist

• [x] I've added tests for this change
• [x] I've added a Changelog entry
• [x] I've updated a documentation (Readme)

[tagirahmad]

Is it ok, @palkan?

[palkan]

LGTM 👍 Let's add a changelog entry and update the docs.

[palkan]

Thanks!