Replace deprecated library function os.popen() with subprocess
Replace deprecated library function os.popen() with subprocess

os.popen() is deprecated since python 2.6.
Resolved with use of subprocess module.

Change-Id: Ifc456fa960c37bdfdf4b9635eb4b069b443b6a4b
Closes-Bug: #1529836

ozamiatin/oslo.messaging,dukhlov/oslo.messaging,ozamiatin/oslo.messaging,dukhlov/oslo.messaging