Add return of event in track method

[woto]

Hi, we need get access to the created event. What do you think if there

ahoy/lib/ahoy/database_store.rb

Lines 20 to 21 in 17d977d

	begin
	event.save!

will be instead?

        begin
          event.save!
          event

or at least to assign last tracked event somewhere to avoid making request to the DB.

[ankane]

Hi @woto, thanks for the PR. Can you share more about your use case?

[woto]

@ankane Sure, we want to send info about ahoy event (at least id) to external tracking/metrics systems.

By the second option of getting access to the event, I meant something like this:

        tracker.track('event', {})
        ahoy_visit = tracker.visit
        ahoy_event = tracker.event

like it is done for the tracker.visit.