Adding .gitlab-ci.yml for GitLab

This patch introduces .gitlab-ci.yml file to
test the e2e deployment and RC2 testcases suite
in GitLab.

Change-Id: If9e39d42a433611e35ced296c60dcb4d2ffbe5a2
Signed-off-by: Rihab Banday <rihab.banday@ericsson.com>
Reviewed-on: https://gerrit.opnfv.org/gerrit/c/kuberef/+/70894
Tested-by: jenkins-ci <jenkins-opnfv-ci@opnfv.org>
Tested-by: Georg Kunz <georg.kunz@ericsson.com>
Reviewed-by: Victor Morales <chipahuac@hotmail.com>
Reviewed-by: Georg Kunz <georg.kunz@ericsson.com>