Update neutron-adv-test to use openstackclient commands

There were a few references of keystoneclient in
exercises/neutron-adv-test.sh, this patch will change those
commands to their openstackclient equivalents.

Change-Id: I88892fcfacd3dd6354ec269b270cee3da358447a
Edit docs to include git.openstack.org url

This patch proposes a change to clone the devstack repository from
git://git.openstack.org rather than https://github.com since git urls
are faster than https and put less loads on the server.

Change-Id: I7fe6a0f81be812dacfef575caa1cf0ae800f9a29
Merge "Edit docs to include git.openstack.org url"
Merge "Update neutron-adv-test to use openstackclient commands"