Refactor amqp provider selection for HA deployment

- Add amqp_provider parameter to quickstack::pacemaker::params, so
  staypuft can pass the UI selection in properly

- Remove include_{rabbitmq,qpid} parameters and replace with unified
  include_amqp parameters instead.

- Use above changes to toggle the rabbitmq and qpid classes on and off
  accordingly.
Merge pull request #312 from jeckersb/ha_amqp_provider

Refactor amqp provider selection for HA deployment