Add configuration list command

[Terry Howe]

Add a 'configuration list' command to go allow with 'configuration show'. List all the clouds, probably just the names.

[Terry Howe (thowe-g)]

I would expect the 'openstack configuration list' command to list all the clouds in your clouds.yaml. Something like:
    $ os configuration list
    +---------------+
    | Name |
    +---------------+
    | rax |
    | blue |
    +---------------+

[Terry Howe (thowe-g)]

I can't think of anything else to have in the list, region maybe? Username maybe?

[Steve Martinelli (stevemar)]

i think username, project name, and region name should be added, but we need to make sure things don't break if those values don't exist

[Steve Martinelli (stevemar)]

alternatively, those could be added if the user passes in --long

[Nandini (nandini-tata)]

understanding it better! So, in the process, we don't need to touch clouds-public.yaml at all?

[Steve Martinelli (stevemar)]

you got it!

We parse the clouds.yaml file here: https://github.com/openstack/python-openstackclient/blob/6dfa304617255f8f5d3011ee92648e3c2dbbe2fa/openstackclient/shell.py#L237-L251

the new function should go here: https://github.com/openstack/python-openstackclient/blob/master/openstackclient/common/configuration.py

and docs along with the patch here: https://github.com/openstack/python-openstackclient/blob/master/doc/source/command-objects/configuration.rst