Bring delete and update functions to keystone module
Bring delete and update functions to keystone module

This commit adds "state" parameter in the keystone module for
its ensure_endpoint command.

This is the state parameter behavior:
- When not set or set to present, it will ensure the endpoint
  with the URL given will be present in keystone

- When set to update, it will ensure that the same kind of
  endpoint gets its url changed if it was different. If there
  was no endpoint of the same kind, the module will create the
  endpoint

- When set to absent, the module will delete the endpoint with
  the given url.

Closes-Bug: #1426191
Change-Id: Ie5e715d02f2d5fb96ceeb2c3e368090aa4702599

openstack/openstack-ansible-plugins,os-cloud/openstack-ansible-plugins,openstack/openstack-ansible-plugins,os-cloud/openstack-ansible-plugins