CSIT-841 Optimize creating of vnf-agent docker image Part I

- Optimize building of prod_vpp_agent docker image by using
  dev_vpp_agent docker image pulled from dockerhub/ligato instead of
  building on slave.
- Add detailed logs from every POD deployed in namespace.
- Hardening condition for considering PODs Running.

Change-Id: I9f771d6365d38fef2ec2e00ab642853e6a44ad03
Signed-off-by: Peter Mikus <pmikus@cisco.com>