Remove ribs.factory

[btjanaka]

Description

ribs.factory is never used and requires more complexity as the library grows. This PR removes the factory.

TODO

Questions

Status

• [x] I have read the guidelines in CONTRIBUTING.md.
• [x] I have formatted my code using yapf
• [x] I have tested my code by running pytest
• [x] I have linted my code with pylint
• [x] I have added a one-line description of my change to the changelog in HISTORY.md.
• [x] This PR is ready to go