Add support for the neutron client in the osclients object

This patch adds the ability to request the neutron client from
osclients' object.

Blueprint benchmark-context-tenant-quotas
Blueprint benchmark-scenarios-for-neutron

Change-Id: I1aec30165c94b45c9a3fb0193bf7c8acf3af3dc4
Merge "Add support for the neutron client in the osclients object"