instance lifecycle events

[matt-beanland]

instance events introduced the event and the ability to fire from instance maintaining the chain.

Enhance so that instance lifecycle fires events automatically, in particular service/resource creation, stateChange, attributeValueChange, deletion.

[matt-beanland]

Possibly Event fire_event? should work out whether an event needs to be fired and fire the event of the correct type, which means we may not create a event at all (if nothing has changed).
We need to look at the firing_snapshot on the last event, and compare with the firing_snapshot to determine whether we have an attributeValueChangeEvent.
If instance is new the event should be a createEvent. If the instance is being deleted we need to raise a deleteEvent.

[matt-beanland]

Another approach would be to call explicitly in the action. For a state change event, we only want to fire the event if the state actually changes. For an update, say annotate, we would chain the fire event action with type: :serviceAttributeValueChange or :resourceAttributeValueChange.

[matt-beanland]

Rebased including place and party relationships (#47)

[matt-beanland]

Wrote a FireEvent change however it expects the instance to already exist so doesn't work with create instance. Perhaps needs to be run in after hook?