Enos

* Fix requests/urllib3 docker bug
* Make sure openstack init script fails if any command fails
* Fix flavor creation with OpenStack Wallaby

* Fix 'enos info' by serializing more Enoslib objects

- fix Docker installation
- when creating a configuration template, use a fixed version of kolla-ansible (so that templates are not affected when future versions of Enos update the default version of kolla-ansible)
- add support for kolla-ansible 12 (Openstack Wallaby), which is now the default
- add support for Debian 11 base image
- add support for Python 3.10 and 3.11
- drop support for Python 3.7

- Modularization of tasks. Task can now be imported in another python project to build uppon enos.
- Enhance the cli with new error messages and colors.
- Lazy load enoslib to speed up the print of help messages.

Major changes:
- Use python3.7 for enos and kolla-ansible (7c6365f)
- Move to Debian buster (10) as base OS (7c6365f)
- Move to kolla-ansible 10 -- OpenStack Ussuri release (7c6365f)
- Modularize KollaAnsible, Rally and Shaker code into dedicated modules (7c6365f, 8655757)
- Update the code of Rally to the latest version (Fix 338)
- Use enoslib docker service (Fix 337)
- `enos new` generates a reservation.yaml specific to the provider (Fix 174)
- Add a "quick start" to the README (b83bfaf)
- Move to python poetry for packaging (189e521)
- Simplify the implementation of `enos up` by calling `kolla-ansible bootstrap-servers` (7c6365f)
- Make travis tests with python 3.7 to 3.9 (8b2e434, 3a6bc97)
- json export of the environment correctly handle pathlib.Path (Fix 334)
- `enos init` deploys the latest cirros image and Debian buster (available inside glance under the name `debian-10`)

Breaking changes:
- kolla -on-the-fly- patching has been removed in favor of the ability to deploy a custom kolla-ansible (for more information, see commit message 7c6365f)
- ceph support has been dropped in favor of enoslib docker service (efea725) -- ceph was mainly a valid option for G5k. The new G5k docker mirror is a better option.
- inventory.sample and workload has been moved to the 'resources' directory.
- `enos new` generates a `reservation.yaml` file in the current directory instead of outputting the file content.
- All functional tests are broken ... dunno how to test them (there is a wip to fix them, see rcherrueau/enos69883b8)

At a glance

EnOs version 6.0.0 (stable/stein)

- Release notes : https://github.com/BeyondTheClouds/enos/releases/tag/6.0.0
- Pypi package : https://pypi.python.org/pypi/enos/6.0.0
- Documentation : https://enos.readthedocs.io/en/6.0.0

Release notes (most noticeable changes)

- Add a tutorial to use OpenStack SDK
- Add a build command for g5k, vmong5k and vagrant (allow to build preconfigured environment)
- Migrate to EnOSlib3