Modify Pulp Smash for the Pulp 3 transition to RQ

[dralley]

Pulp 3 is planning to switch from tasking using Celery to tasking using RQ. This means that Pulp will no longer require a message broker like Qpid or RabbitMQ.

This won't require too much modification to Pulp Smash, but the main ones I can think of are:

• There's no need to ask whether the user is using Qpid or RabbitMQ, when using pulp-smash settings create with Pulp 3

• There's no need for the amqp_broker section in the settings.json

• The status API page will change.

There is a PR open to make these changes (#960), and this issue might not necessarily be an exhaustive list.

[nixocio]

Besides that, the options celerybeat, mongod, and squid should be evaluate as well.