Revert "Call stopListening on module stop"

This reverts commit b8075a2fef4d366d19ba986cd201eb904497d69f.

per comments from @disruptek about this being breaking from him. 
https://github.com/marionettejs/backbone.marionette/pull/1022#issuecomment-39014298

The "breaking" change was due to the module docs being vague.

This behavior will be placed into the 2.x release as part of the larger module rework to introduce a more fine grained concept of a lifecycle and a "Stop" much like  https://github.com/marionettejs/backbone.marionette/pull/801

As modules stand right now they represent a significant potential for memory headaches, since right now "stop" does not clear the modules footprint as @dmytroyarmak pointed out.