Make outbound SMS response asynchronous

[ycombinator]

Currently, when we receive an inbound SMS, we respond synchronously. Making the outbound response asynchronous has a couple of benefits:

• Using a queue to track pending outbound deliveries would allow us to control the queue (pause, resume, skip items, etc.)
• The same queue could be utilized for outbound messages initiated by Hermes (as opposed to a response to an inbound message).
• Initially, we could email ourselves the text of the SMS to be delivered and queue it up for delivery a few minutes later. This gives us an opportunity to review the text of the message and intercept the delivery if necessary.

[ycombinator]

Consider using https://npmjs.org/package/amqp in conjunction with https://addons.heroku.com/cloudamqp.