CLOUDSTACK-6721: VolumeApiServiceImpl is sending wrong type for
updateAsyncJobAttachment

fix sends 'Volume' instead of 'volume'

Conflicts:
	server/src/com/cloud/storage/VolumeApiServiceImpl.java
CLOUDSTACK-6720: Async job events are not published on event bus

fix ensures publishOnEventBus() is called on submit, update, complete
phase of job procesing