Replace subprocess.check_output with Popen
Replace subprocess.check_output with Popen

The check_output method does not exist in python 2.6

Fixes bug 1029014

Change-Id: I1ee24fa2029f21706924cc19dfcbc41655b022e6

hyakuhei/cleantox,zancas/hacking,hyakuhei/cleantox,openstack-dev/hacking,emonty/oslo-hacking,emonty/oslo-hacking,openstack-dev/hacking,zancas/hacking