Don't create the grails directory structure when running grails commands

Specifically for plugins, It would be nice if grails didn't create any missing directory structure when running package-plugin and test-app. However it would be nice if the only grails commands that created the grails directory structure are create-plugin and create-app.

If grails plans to move forward using plugins to modularize projects have all of the extra folders is un-necessary when all that may be needed is grails-app/domain.