Support for node v0.12.4

[bmjjr]

Upgraded node to v0.12.4 and seems Kal broke.

Below is issue:

me_MBP:kalsandbox me$ kal test.kal /usr/local/lib/node_modules/kal/compiled/kal.js:1 box=vm.createContext(global);else if(!(sandbox instanceof vm.Script.createCont ^ TypeError: undefined is not a function at Object.makeSandbox (/usr/local/lib/node_modules/kal/compiled/kal.js:1:1209) at Object.kal_eval as eval at Object.run (/usr/local/lib/node_modules/kal/compiled/command.js:1:2421) at Object. (/usr/local/lib/node_modules/kal/scripts/kal:7:27) at Module._compile (module.js:460:26) at Object.Module._extensions..js (module.js:478:10) at Module.load (module.js:355:32) at Function.Module._load (module.js:310:12) at Function.Module.runMain (module.js:501:10) at startup (node.js:129:16)