Add reCAPTCHA and optional disable flag for user registration

[dismantl]

Status

Ready for review

Description of Changes

This allows you to completely disable user registration by setting the environment variable DISABLE_REGISTRATION. Additionally, you can add Google reCAPTCHA v3 to the user registration page by setting the RECAPTCHA_V3_SITE_KEY, RECAPTCHA_V3_SECRET_KEY, and optionally RECAPTCHA_V3_THRESHOLD environment variables.

To Test

Set up a recaptcha v3 site with Google (using localhost and 127.0.0.1 for domain names) and add the site key and secret key to the .env file using above environment variables. Then make dev and register a user. You can then see the recaptcha score assigned to that registration by checking the docker logs. You should see something like this:

[2020-07-20 18:14:31,903] INFO in recaptcha3: {'success': True, 'challenge_ts': '2020-07-20T18:14:17Z', 'hostname': 'localhost', 'score': 0.9, 'action': 'registration'}

Notes for Deployment

Screenshots (if appropriate)

Tests and linting

• I have rebased my changes on current develop

• pytests pass in the development environment on my local machine

• flake8 checks pass