Switch to Python Virtual Environment

Virtual Environments allow the python modules installation without
affecting the hosting node. This helps to control dependencies required
by this project.

Signed-off-by: Victor Morales <v.morales@samsung.com>
Change-Id: Ib53d9dd335a4707ff863a6fd732d23d323513430
Reviewed-on: https://gerrit.opnfv.org/gerrit/c/kuberef/+/71195
Tested-by: jenkins-ci <jenkins-opnfv-ci@opnfv.org>
Reviewed-by: Michael Pedersen <michaelx.pedersen@intel.com>
Reviewed-by: Rihab Banday <rihab.banday@ericsson.com>