Refs: #3874

Minimum config file:
[global]
token = <user token>

Changes:

- Only one field "cli" for user command specs, to map command groups to CLIs:

[cli]
 user = astakos
 file = pithos
 server = cyclades
...

- Specify client services/apis and versions.
 General format:
 [client]
  type = <service>
  version = <api version>

 Example:
 [cyclades]
  type = compute
  version = v2.0