Make CHISTORY temp - Githubissues

This PR:

Creates a temporary directory in get_events.sh using mktemp to hold CHISTORY.TXT while parsing instead of downloading it.
Moves get_event_timestamp() logic from download.sh to get_events.sh
get_events.sh now returns event_id, date_dir, event_timestamp

acep-uaf / camio-meter-streams