adds groovy-eval-definition, groovy-eval-buffer

adds `groovy-eval-definition`,  maps to `C-M-x` 
adds `groovy-eval-buffer`,      maps to `C-c C-k`

`groovy-eval-definition` derived from enhanced Scala mode:
https://github.com/ensime/ensime-src/blob/master/src/main/elisp/ensime-inf.el

`groovy-eval-buffer` key binding matches Clojure eval-buffer:
https://github.com/clojure-emacs/cider