EventSearch.eventTypes will (soon be) a has-many.
Demonstrate that new event searches have editable location scope.

(They currently don't: the "default to all locations" code is broken.)
Move the "select all for new searches" code to the controller.

This avoids timing problems inherent with code like

  Pancakes.StudyLocation.forEach (l) ->
    search.get('eventLocations').addObject l