disable should accept message parameter

[komlenic]

I'm not sure how to best handle instances where specific actions (such as disable) will require additional input. The idea of all commands following the 'drubs action nodes' pattern could probably be maintained fine if the command for drubs disable looked like this:

drubs disable [nodes] --message="My message here"

--message, -m would be an optional argument only to the disable action/command.

This is probably how this needs to be handled.