Fix for the deprecated library function
Fix for the deprecated library function

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

Change-Id: Ia44f4e37d927c4028013943146e1f922909690df

stackforge/stackalytics,openstack/stackalytics,stackforge/stackalytics,openstack/stackalytics,stackforge/stackalytics,Mirantis/stackalytics,Mirantis/stackalytics,0xf2/stackalytics,openstack/stackalytics,0xf2/stackalytics,openstack/stackalytics,0xf2/stackalytics,0xf2/stackalytics,Mirantis/stackalytics