The IvyResources task is not compatible with Ant 1.6. Since the minimal requirement is still Ant 1.6, we should print a warning when the antlib is loaded instead of throwing an error.
The IvyResources task is not compatible with Ant 1.6. Since the minimal requirement is still Ant 1.6, we should print a warning when the antlib is loaded instead of throwing an error.

git-svn-id: bddd0b838a5b7898c5897d85c562f956f46262e5@1308204 13f79535-47bb-0310-9956-ffa450edef68

pantsbuild/ivy,pantsbuild/ivy