3rd party ci: Create jobs for ODL netvirt testing in OPNFV

3rd party ci: Create jobs for ODL netvirt testing in OPNFV

This change creates basic job structure for ODL netvirt testing in OPNFV.
The job should be triggered once the below job is completed
    https://jenkins.opendaylight.org/releng/job/netvirt-patch-test-current-carbon
and fetch the artifact that is already built by the job. The build result
codes OPNFV is interested in are SUCCESSFUL and UNSTABLE.

Once the job gets triggered, the build URL will be fetched from ODL Gerrit using
Gerrit REST API and the artifact will be downloaded from ODL Jenkins.
The downloaded artifacts will then be installed on the Apex environment.

There are 3 points that need to be highlighted.

- The Apex environment will be created using the promoted snaphots/qcow2
images and already deployed VMs will be brought up. See below for the details.
    https://jira.opnfv.org/browse/APEX-360

- The hardcoded values in download-netvirt-artifact.sh are there to get the
basics in place. (branch name, job name, etc.) Once things work as expected,
they will be made dynamic.

- A workaround using Gerrit REST API is put in place to get build number of the
job netvirt-patch-test-current-carbon to download the artifact.
The reason why we use Gerrit REST API is that the OPNFV Jenkins has an older
version of Gerrit Trigger Plugin which lacks feature that injects review
comments as environment variables. Upgrading Gerrit Trigger Plugin will not
help either since OpenStack JJB does not support the new version of Gerrit
Trigger Plugin and does not generate the new job XML.

JIRA: RELENG-171

Change-Id: I7ff8c5809dcb2e8ffa5c7c5aeb9cdf70e4e7e2f4
Signed-off-by: Fatih Degirmenci <fatih.degirmenci@ericsson.com>