This change adds support for the GetAttributeList operation to the
KMIPProxy client. It adds a new result object for the operation along
with an integration test demonstrating how the operation can be used.
Client unit test cases are also included.
This change adds a pytest config argument, allowing the integration test
suite to be run with the client configured with a specific section from
the PyKMIP configuration file. A simple integration test class is added
to demonstrate how to use the client created using the config argument.
To run the integration test suite with a specific configuration, use:
$ tox -e integration -- --config <config-section>
where <config-section> is the name of the config file section to use for
the PyKMIP client.
