OSTF-167: Non destructive RabbitMQ tests for HA configuration

* amqp client was added to fuel_health/common

    This client allows provide following actions
    with RabbitMQ: create a queue and send/receive message.

    Also there are several utility methods for clearin
    the queue, and closing it safely
* setup.py file wa updated with pika package
    is needed for amqp client

* fuel_health/tests/test_rabbit was addede with new
    test checks there is rabbit cluster,
    it contains the right number of nodes
    and present at tha same view on all the controllers

* it was found current SSH client does not support sudo
    commands because of tty is absend. SSH Client was refactored
    to invoke virtual terminal and avoid the problems

All the tests were executed on devstack, FuelWeb and FW HA labs.
verify method from the mixen was added