Make compatible wth Rubinius 2.1.1

So I got interested in playing around a bit with this language, found that it wasn't _quite_ compatible with the latest version of Rubinius (`2.1.1`, which was released fairly recently), and took matters into my own hands to get some test scripts running.  I took the constant 'path' used (`Rubinius::ToolSet.current::TS::{tool_name}`) from the source code of the rubinius-compiler gem. 

Hope my efforts can help some future looky-loo.