IVY-1455 Prevent incorrect ivy mediators from being applied during conflict resolution.

Prior to this, the mediators to be applied depended on the location where a
conflict was detected, rather than the declaration location.


git-svn-id: https://svn.apache.org/repos/asf/ant/ivy/core/trunk@1553745 13f79535-47bb-0310-9956-ffa450edef68
Document that threading is unsupported, and disable test covering same

git-svn-id: https://svn.apache.org/repos/asf/ant/ivy/core/trunk@1553747 13f79535-47bb-0310-9956-ffa450edef68
Document IVY-1455 in CHANGES.txt

git-svn-id: https://svn.apache.org/repos/asf/ant/ivy/core/trunk@1553748 13f79535-47bb-0310-9956-ffa450edef68