Fix updating of f/b information when date changes.

Fixes updating freebusy information when changing date via either
the textbox or date picker on new events before saving (both were broken),
as well as via the date picker when editing existing events.

Bug: 12676
$event is type-hinted, it can never be an array.
One more place we don't need an is_array check.
Fix display of resource response icons.
Fix showing "yesterday" as free, when it should be unknown.
Property compare before/after resource arrays.

array_merge won't work since the $values are hashes.
Events added to a resource calendar should always be STATUS_CONFIRMED
Don't bother checking resource availability if event is cancelled.
Cancel the event on the resource's calendar.
Fix this in the correct place.
Merge from master: must be case insensitive.
Method signature must match the parent class.
Body is optional, don't include it if we don't have a description.
Fix css class.
Getting caught up on some merges from master.