better visibility if Twilio blocks calls from an account

[alanb2718]

We had an incident where something was messed up on the configuration for one of our area's Twilio account. It would be nice to have better visibility from yap that there was a problem, in case something like this happens again.

Yap worked ok for receiving calls and reading back meeting information. If the caller asked to speak with a volunteer, the caller would hear the phone ringing, which would go on indefinitely, even though the yap setting was blast then send to voicemail. No volunteers got a call. The only indication that something was wrong is an entry in the laravel log:
Twilio\Exceptions\RestException: [HTTP 400] Unable to create record: Account not allowed to call [number redacted]

We never did figure out what was misconfigured on that Twilio account. (Twilio support wasn't figuring it out, and we bailed after a bit and just got a new account, which fixed the problem.)