Data Model - Like

[kbitgood]

Motivation

The data models must be completed before their respective API endpoints can be written. This issue will track the progress of the Like data model.

Plan of action

Create the model class(es) for the Like from the spec defined in this google doc.

Criteria to close

All of the attributes of the podcast data model defined in the google doc must be present. All of the relationships to data model classes already created should also be present. Any relationships to data model classes that have not yet been created should have a TODO comment as a placeholder.