run_test.sh in python-fuelclient do not allow to select desired tests correctly

[Sebastian Kalinowski]

run_tests.sh has an option '-t' that allows to select tests to run.

It does not work with multiple tests:
$ ./run_test.sh -t path/to/tests_a.py path/to/tests_b.py - runs only "path/to/tests_a.py"

And it does not work with nosetests test selectors:
$ ./run_test.sh -t path/to/tests_a.py:TestCase.test_method
Error: Specified tests were not found.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/155748

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/155748
Committed: https://git.openstack.org/cgit/stackforge/python-fuelclient/commit/?id=6270ce08c7c3729f87eccf1f2d41e7e12250b5ee
Submitter: Jenkins
Branch: master

commit 6270ce08c7c3729f87eccf1f2d41e7e12250b5ee
Author: Bartłomiej Piotrowski <email address hidden>
Date: Fri Feb 13 14:53:49 2015 +0100

    Allow to specify multiple tests in run_tests.sh

    Disable checking for unbound variables, as there is possibility that no
    tests were specified. Example invocation:

    run_tests.sh -n -t fuelclient/tests/test_client.py:TestAuthentication.test_wrong_credentials \
    -t fuelclient/tests/test_client.py:TestDownloadUploadNodeAttributes

    Additionally align shifts in getopt loop and remove
    dead return from tox invocation.

    DocImpact
    Change-Id: I83a52b5f5467c9ea92dfafba9b92b700f7e76a38
    Closes-Bug: 1420664