Fix Grunt task for test.
Add an ObservableBuffer.

An ObservableBuffer mimicks an observable while it is not available yet.
ObservableListener replaces this for more methods.

listenTo, stopListening and listenToOnce
Module communication.

Every module can communicate with it's parent with `parent` pubsub or
just by prefixing the event name with 'parent!'.
Module#connect validity check was meaningless.

No need to check as any object would be given by keyValueOrObject
helper.
It would always end up with a string as first argument.
Module forwards stop and standy to submodules.