Remove The Need For The Ant Build For Grails Core

Our functional tests are currently built with Ant. The functional test build will build Grails core using Ant. We need to fix that so we can remove the Ant build from Grails core. As it is right now, we have to manage both the Ant and Gradle builds. This could probably be accomplished while continuing to use Ant for the functional tests build but this seems like a good opportunity to remove Ant from the functional test build as well.