reverted back to groovy 2.3.3 because of compatibility with gradle 2.0
reverted back to groovy 2.3.3 because of compatibility with gradle 2.0

cwardgar/gretty,WilliamRen/gretty,akhikhl/gretty,cwardgar/gretty,saladinkzn/gretty,aya-eiya/gretty,akhikhl/gretty,cwardgar/gretty,akhikhl/gretty