Make "Land Revision" button state consistent, prevent non-accepted lands
Ref T182. Make the disabled state of the button more accurately reflect whether clicking it will work.
Don't allow "land" to proceed unless the revision is accepted.
Test Plan: Saw button in disabled state, clicked it, got "only accepted revisions" message.
Reviewed By: chad
Maniphest Tasks: T182
Differential Revision: https://secure.phabricator.com/D14350