replace the native quickstart inventory role with redhat-openstack/ansible-role-tripleo-inventory

Replace the native quickstart inventory role with redhat-openstack/ansible-role-tripleo-inventory.

The native quickstart inventory role does not inventory the overcloud nodes, which is critical for post overcloud deployment tasks and collecting logs from the overcloud. Using a composable role also has advantages in that it can be replaced quite easily.

The ansible-role-tripleo-inventory role is currently gated by a POC jobs [1]. This change should wait until this moves from POC to production. In addition the ansible-role-tripleo-inventory role is used by the ooo-usbkey [2]. Using the third party role in the main playbook would help to ensure the quality of the usbkey as well.

The change would look like:
https://www.diffchecker.com/kuocbwwt

An additional change to the requirements.txt would be required.
The contents in the usb_requirements file would need to in the default requirements.txt
https://github.com/openstack/tripleo-quickstart/blob/master/ci-scripts/usbkey/usb_requirements.txt

[1] https://ci.centos.org/job/poc-apetrich-tripleo-quickstart-roles-gate-mitaka/
[2] https://github.com/openstack/tripleo-quickstart/tree/master/ci-scripts/usbkey
https://ci.centos.org/job/poc-apetrich-tripleo-quickstart-roles-gate-liberty/