Dont drop events during gather job info

Seen with syndic, but in theory affects all setups. When a we call gather_job_info if an event comes in for the main job we sometimes discard the event whilst we are looking for the gather_job_info event. To work around I've made gather_job_info add events for the main job to the pending_events list. get_event now always checks that list for events matching it's tag.

This was originally developed on my 2014.1 branch. Upon merging it I found the RAET stuff I've tried to standardise the interface across the two SaltEvent classes, but I've been unable to test the RAET version of this.