Revert "Upgrade to Aether 0.9.0.M3, which has now moved to Eclipse. This fixes GRAILS-10638 "Grails loses dependency if inline plugin has the same dependency in test scope""

This reverts commit 1be19666c1c28aa5a3168dada41bf56edca9b485.

I am only temporarily reverting this change to allow a build cycle to run through the CI server while the problems with this commit are being investigated.