Keystonemiddleware

Keystone client is deprecating keystoneclient.middleware.auth_token in favor of keystonemiddleware.auth_token. Since we are using auth tokens,
install this additional python library so we can authenticate auth tokens using it.
I know it'll not look like the rest of the tasks here, but could you use:
```
command: pip install ...
```
instead of the `action:` syntax?