An initial implementation of an AMQP 1.0 based messaging driver

The key driver interfaces are implemented in the ProtonDriver class in
driver.py.  The logic for interfacing with Pyngus in order to
send/receive messages, manage AMQP connections and links, and handle
protocol events is in controller.py.  eventloop.py is a fairly generic
socket connection and I/O processor which runs in its own thread.
controller.py uses the eventloop.py thread to schedule subscription
and message send requests from the driver, as well as handle all
protocol event callbacks coming from Pyngus.

Included in this patch are a set of functional tests that can be run
under tox (tox -eamqp1).  These tests fully exercise the new driver,
from the driver API down to the 'wire' - nothing in the driver is
mocked out.  The functional tests implement a simple loopback test
broker, which allows the driver to send and receive messages via the
local network.  All RPC call patterns, RPC timeouts, and even broker
failover are verified by the included functional tests.

This driver uses the Pyngus module, which is a pure-python client API
built on the Proton AMQP 1.0 protocol engine library from the Apache
Qpid project.  Pyngus is available via pypi.python.org.

This driver introduces a dependency on the Proton AMQP 1.0 protocol
library, which is a platform-dependent library that must be installed
in order to use this driver and run the functional tests.

Change-Id: I871703e4cdc04cee3e6c214e911c9df464ede2ed
Implements: blueprint amqp10-driver-implementation