Remove the pre-outputformats old-fashioned 'format' option from config-list command.

Before this change, the help output was:

 --format                                  Define the output format.
 Known formats are: json, print_r, and export. Available: list, json,
 var_export, yaml. Default is list.

 Now it is:

  --format=<json>                           Select output format.
  Available: list, json, var_export, yaml. Default is list.
TRUE boolean.
Upgrade update_info to a first class engine.
Honour 'add-options-to-command' for engine type options.
Fix management of engine load failure.

Also improve docs and improve readability.
Enable engines to declare dependencies on drupal modules. Remove dependency on update.module in commands that use the update_info engine.
Remove leftover function that we stop using in 2010!.

Refer to commit 8d8433