run_tests starts selenium no matter if the flag --with-selenium is used

[Matthias Runge]

When running tests without using the parameter --with-selenium errors show up in the log file:

ERROR: Failure: ImportError (No module named selenium.webdriver)

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/61059

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/61059
Committed: http://github.com/openstack/horizon/commit/f95b2b68d2219f717ae0e604af7e61e1a24dde6e
Submitter: Jenkins
Branch: master

commit f95b2b68d2219f717ae0e604af7e61e1a24dde6e
Author: Matthias Runge <email address hidden>
Date: Tue Dec 10 10:37:55 2013 +0100

    Run selenium tests only when requested

    In some environments, it's not wanted or possible
    to execute selenium tests. These are only executed, if
    --with-selenium is specified.

    Change-Id: I39c40ac1feb64565f0bcbc97f6345d203b1d816e
    Closes-Bug: 1259072