fuel-client unit tests require access to Nailgun API

[Roman Prykhodchenko]

Since python-fuelclient is a separate project it should be possible to run unit tests without any external dependencies to ensure the basic quality of the code.

Therefore all invocations of Nailgun API in unit tests should be mocked according to the specification of the API.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/165369

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/165369
Committed: https://git.openstack.org/cgit/stackforge/python-fuelclient/commit/?id=9b0b6ab2f09ff75445550b7210104e21df5d8cd6
Submitter: Jenkins
Branch: master

commit 9b0b6ab2f09ff75445550b7210104e21df5d8cd6
Author: Sylwester Brzeczkowski <email address hidden>
Date: Fri Mar 20 12:55:02 2015 +0100

    run_tests.sh can be executed without Nailgun

    Splitted client's tests into unit and integration.
    Little cleanup in run_tests.sh
    Added new options in run_tests.sh:
    -i|--integration-tests
    -I|--no-integration-tests
    -u|--unit-tests
    -U|--no-unit-tests
    Script executes run_cleanup() and prepare_env() (which
    are responsible for cloning and running nailgun) only
    when running integration tests.

    Closes-Bug: #1409726
    Change-Id: I0685b7534b4a0684ffc932c7d24654548735c9b9