Add hook to formatted name

[shoheitanaka]

I want you to add a hook to the formatted name.
I want a hook that can handle first and last name formats.

All Submissions:

• Does your code follow the Extendables standards?
• Have you written new tests for your changes, as applicable?
• Have you successfully run tests with your changes locally?

Changes proposed in this Pull Request:

I want a hook that can handle first and last name formats.

Closes # .

How to test the changes in this Pull Request:

1. Do test payment at my sandbox site.

Other information:

• Have you checked to ensure there aren't other open Pull Requests for the same update/change?

Changelog entry

• Update - format_name hook added.