[FEATURE ember-testing-triggerEvent-helper] Allow event options to be specified.

Allow specifying options to the event created by the `triggerEvent`
helper. This allows us to utilize `triggerEvent` from `keyEvent`.
Merge pull request #4177 from rjackson/allow_event_options_to_triggerEvent

[FEATURE ember-testing-triggerEvent-helper] Allow event options to be specified.