(MCO-410) Fix direct addressing

MCO-360 broke direct addressing by inadvertently removing the method
call that created the subscription to the mcollective.nodes queue.

This commit replaces that call but also clarifies the intent by adding
comments and wrapping it in a new method call which has been appropriately
named.
Merge pull request #207 from ploubser/mco-410

(MCO-410) Fix direct addressing