Fix logic in resolveConflictsForDocument:

Instead of copying the body over to a new child of the currently-winning leaf, mark the resolved
revision as current and delete all the others.

When a MutableDocumentRevision is returned, delete all except the new revision's parent, and graft
the new revision on there.

* Fix some test cases which were returning detached revisions which no longer make sense in this
algorithm.

* Replace checkOffPreviousWinnerRevisionStatus(rev) with setCurrent(rev,false);

* Fix typo in exception