Switch to Python Virtual Environment

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>