Add "Mark as resolved" button to entity conflict summary box

[matthew-white]

This issue feeds into the larger issue #506, which has a few different aspects. This issue is add the "Mark as resolved" button to the entity conflict summary box, as well as the footer that contains the button. (#530 needs to be completed before this issue.) Clicking the button should show the modal described in the release criteria. This issue is to add the button and the modal, making it possible to mark an entity as resolved from the entity detail page.