add node--event--full

[alisonjo315]

Pro:

• Starter template with standard markup -- yay.
• We have *--full templates on news/spotlights/people -- consistency!

Con:

• Extra, pointless template on sites that don't have any "local" events, only imported-from-localist events (AND don't show those localist events as full/detail pages on the site).
• Unlike news/spotlights/people, events often don't get shown as full/detail pages -- in that sense, they aren't the same as the other three ctypes, so maybe this kind of consistency isn't valuable.