Ticket #40 (new enhancement)

Description

Initially we had these dates be fields in a panel in the Edit interface. However, multiple components composing a content type can be independently scheduled. For example, page properties, and each container on a page can have different release or expiration dates. This makes the panel approach difficult because it can only show the date for one at a time, and it wouldn't be clear which. Instead, by choosing the dates at submission time, it should be clear that the dates will be set for all content changed in that submission. To schedule two changes independently, simply submit them independently (by making one change, submitting, then the other change, and submitting).