65206 - Migrate ant / maven to gradle build
update gradle files and project structure along https://github.com/centic9/poi/tree/gradle_build
remove eclipse IDE project files
remove obsolete record generator files

git-svn-id: https://svn.apache.org/repos/asf/poi/trunk@1888111 13f79535-47bb-0310-9956-ffa450edef68