Require keystone-user/-group for pki_setup

If pki_setup is run as root, require the keystone-user
and keystone-group parameter to be set, to enforce
the proper permissions to be created on the files.

This follows a suggestion in the Bugreport.

Fixes LP Bug #1031372

Change-Id: I00d9e0499d16716af3267914b6b78841f1ad1e0f
Import eventlet patch from oslo.

This was abandoned once before: https://review.openstack.org/#/c/25781/

However this is not to do with packaging. This is required if we use
eventlet subprocess module (like we should be) in jenkins tests for
python2.6.

Also imports patch_tox_venv.py. This is a cutdown version of what would
happen in run_tests.sh but for tox environments which is how jenkins
runs tests now.

Change-Id: I369c3e464dfbe3a754f90db58785e97ac87b36c0
Merge "Require keystone-user/-group for pki_setup"
Merge "Import eventlet patch from oslo."