class Thor::Runner

def method_missing(meth, *args)


Thor::Runner is then responsable for finding the task in all classes.
If a task is not found on Thor::Runner, method missing is invoked and 
def method_missing(meth, *args)
  meth = meth.to_s
  initialize_thorfiles(meth)
  klass, task = Thor::Util.namespace_to_thor_class_and_task(meth)
  args.unshift(task) if task
  klass.start(args, :shell => shell)
end