Add method to identify and update to new ontology version for oaklib

[tursynay]

Sort out how to download a new version of an ontology when an older version already exists in ~/.data/oaklib/. Note: This can not be done automatically. See https://incatools.github.io/ontology-access-kit/faq/troubleshooting.html#my-cached-sqlite-ontology-is-out-of-date

[twhetzel]

This ticket is in the wrong repo. The working ticket is here include-dcc/harmonica#13

[twhetzel]

The PR for include-dcc/harmonica#13 is merged now include-dcc/harmonica#14