Add a flag to skip certificate verification

[ob-stripe]

Reviewers

r? @aarongreen-stripe @brandur-stripe @tomer-stripe
cc @stripe/dev-platform

Summary

Adds a --skip-verify flag to the listen command that disables certificate verification when forwarding to an HTTPS endpoint.

Fixes #108.

I've tested this manually:

$ ./stripe listen --forward-to https://localhost:4443
> Ready! Your webhook signing secret is whsec_... (^C to quit)
[Thu, 15 Aug 2019 14:18:28 PDT]  INFO Received event: evt_123 [type: payment_intent.created]
[Thu, 15 Aug 2019 14:18:28 PDT] ERROR Failed to POST event to local endpoint, error = Post https://localhost:4443: x509: certificate is valid for stripe.com, not localhost

$ ./stripe listen --forward-to https://localhost:4443 --skip-verify
> Ready! Your webhook signing secret is whsec_... (^C to quit)
[Thu, 15 Aug 2019 14:18:45 PDT]  INFO Received event: evt_123 [type: payment_intent.created]
[Thu, 15 Aug 2019 14:18:45 PDT]  INFO Got response from local endpoint, status=501

[brandur-stripe]

LGTM.

[ob-stripe]

Thanks Brandur!

[ob-stripe]

Released as 0.4.5.