Unable to renew once certificates have already expired

[lyarwood]

An --ignore-cert-errors switch might be useful here as I'd assume this would be a pretty common use case.

# gitlab-le --email foo@bar.com --token 1234 --domain blog.example.com --repository https://gitlab.com/foo/bar.gitlab.io  --production
[..]
[letiny-core] setChallenge Error:
RequestError: Error: certificate has expired
    at new RequestError (/usr/lib/node_modules/gitlab-letsencrypt/node_modules/request-promise-core/lib/errors.js:14:15)
    at Request.plumbing.callback (/usr/lib/node_modules/gitlab-letsencrypt/node_modules/request-promise-core/lib/plumbing.js:87:29)
    at Request.RP$callback [as _callback] (/usr/lib/node_modules/gitlab-letsencrypt/node_modules/request-promise-core/lib/plumbing.js:46:31)
    at self.callback (/usr/lib/node_modules/gitlab-letsencrypt/node_modules/request/request.js:188:22)
    at Request.emit (events.js:182:13)
    at Request.onRequestError (/usr/lib/node_modules/gitlab-letsencrypt/node_modules/request/request.js:884:8)
    at ClientRequest.emit (events.js:182:13)
    at TLSSocket.socketErrorListener (_http_client.js:391:9)
    at TLSSocket.emit (events.js:182:13)
    at emitErrorNT (internal/streams/destroy.js:82:8)
    at emitErrorAndCloseNT (internal/streams/destroy.js:50:3)
    at process._tickCallback (internal/process/next_tick.js:63:19)
Error: certificate has expired