Move request_and_transport to the Client

This patch moves the `_get_transport` and `request_and_transport` method
to the client. Both method are useful for other resources like Message,
for example.

This patch also moves the is_functional logic to the BaseTest class and
splits unittests from functional tests.

Partially-Implements: python-marconiclient-v1
Change-Id: Iaf56c234291b355c98817feee5644a5dd07c0b7f
Add a Client 'instantiator'

This function mocks a class constructor but returns a client instance
for the specified version. This reduces the number of imports needed to
use the API and makes it easier to migrate from one version to the
other.

Change-Id: I20bb9adef4fa4f6bb87c53020454c791d765c389
Partially-Implements: python-marconiclient-v1
Add a base test class for the queues package

Tests for `Messages` and `Claims` will inherit from this new base class
instead of inheriting from the QueueTestBase.

Change-Id: Iddd7d3f538c158f8cf9d8e08654fa524e69e6622
Partially-Implements: python-marconiclient-v1
Add `deserialized_content` to the response

This is a helper method that aims to centralize response's content
deserialization and remove the burden of this process from the client.

Partially-Implements: python-marconiclient-v1
Change-Id: Ia98e9b9cdf5bdd88f9f2cdeda39b49d2192a60eb
Add a Message resource and a MessageIterator

This patch defines the Message resource and the MessageIterator. The
former represents a message unit and the possible operations that can be
executed from that resource. The later allows users to iterate over
Messages' pages and consume all available messages.

The patch also renames queue_id to queue._name which is more consistent
with the API terminology.

NOTE: Functional tests are missing and will be added in a separate
patch.

Change-Id: I8c871e326bd580964f15d4ffc16c6264f9825ba7
Partially-Implements: python-marconiclient-v1
Add missing requests requirement

Change-Id: I681dd9bc819294bbab9f28345bc46939c200cbd9
Make pbr only a build-time dependency.

This lets you build python-marconiclient packages that don't require pbr
to be installed at all. You would need pbr on the machine running
rpmbuild / debuild, but not on the machines that install the packages.

Unfortunately, this does not make python-marconiclient able to be
installed via pip 0.3.1 on Lucid; you'll need to uninstall the system
python-pip package and install a new pip some other way. Given that pip
< 1.3 doesn't perform SSL certificate validation for pypi (trivial MITM
attack, anyone?), you'd probably want to get a new pip anyway.

Change-Id: I2fb160b6dd446f1fc72eed2371db1afcb00b9e52
Merge branch 'master' of https://github.com/FlaPer87/python-marconiclient