Create error for upgrading to same version.
Add --diff option to rose-date.
Merge pull request #1306 from arjclark/fix.upgrade_same_version_msg

rose app-upgrade: better error message for upgrade to same version
Tweak if ordering following review.
Add test for offsetting.
Merge pull request #1316 from arjclark/rose_date_diff

rose date: add --diff option