Don't use our own queues for pulse

[marco-c]

We can directly rely on AMQP queues.

[marco-c]

It would:

1. Remove one level of indirection, as we don't need to push to Redis and pull from Redis;
2. Be more performant in general, as it's made specifically for these purposes (in fact, we could even have an implementation of our queues relying on AMQP instead of Redis).

[La0]

If we don't do that, we should investigate

• having one channel for each listener per the doc
• having a consumer_tag in basic_consume (which will also be available in the envelope), so each consumer can be tagged.
• looking into librabbitmq per Use librabbitmq instead of aioamqp #21 and see how it changes that part of the code

Reference : #32 (review)

[marco-c]

Another option is using Redis PubSub.