Organization contributors should be verified to contribute by Curry.

:construction_worker:

Working with @brettchalupa on wrapping this up.

This PR fixes a bug where Curry was not recognizing users who are members of a CCLA Organization on Supermarket.

It does the following:

- [x]  When commit authors are imported into Supermarket from watched repos, a user is authorized to contribute if they have signed the ICLA or CCLA. They are also authorized to contribute if they have accepted an invitation to join a CCLA organization (aka they are a contributor).
- [x] When a user accepts to join an organization, the `Curry::CommitAuthorVerificationWorker` gets run.
- [x] Update the language of Curry + the app to be more explicit about unknown committers, becoming a contributor and signing a CCLA.