Enhancements for spacewalk-manage-channel-lifecycle tool.

We've found some issues in this particular tool and added the following:

1. Now the tool has better organized local configuration, where you can setup your own workflow (i.e. no need to repeat it in the command line and have a human err) and also specify excluded channels in each.

2. The change No.1 also introduces two new options which a) lists all non-default configured workflows and b) selects one.

3. It does not promote to None-channel-name after maximum stage reached.

4. Other minor changes.