GROOVY-6226: Configure Gradle Eclipse plugin for groovy-core

Added/changed package to make Eclipse happy
GROOVY-6226: Configure Gradle Eclipse plugin for groovy-core

Renamed ray to because Eclipse complains about two classes with the same name (the class Ray used by the script and the class rey generated for the script itself)
GROOVY-6226: Configure Gradle Eclipse plugin for groovy-core

Part 2