[WIP] working comments drf api

[rosscdh]

LACKS TESTS.. this is WIP and an attempt to open a discussion on the topic

Changes proposed in this PR:

• integrate basic drf functionality urls and viewsets for comments via api
• integrate openapi specs

Tips for an ideal PR

• You have read our Code of Conduct: https://github.com/pinax/.github/blob/master/CODE_OF_CONDUCT.md
• You have read our Contributing info: https://github.com/pinax/.github/blob/master/CONTRIBUTING.md
• The PR is atomic
• Unit tests have been updated/added, if needed
• App version number has been updated in setup.py (Pinax uses SemVer)
• Change Log has been updated

[KatherineMichel]

Thank you for the PR and for opening a discussion... see my comments on: pinax/pinax-referrals#54