ENOENT error on windows

[dy]

I’m trying to set up testling for es6-collections polyfill fork.

I have latest testling both globally and locally installed.
I have installed xvfb both locally and globally, following #72 (it was a pain on windows, who know).

I don’t know what else I have to install, update or to do, because I still get:

dmitry@WEBDEV-MACHINE /C/Users/dmitry/Dropbox/Projects/es6-collections (master)
$ testling

events.js:72
        throw er; // Unhandled 'error' event
              ^
Error: spawn ENOENT
    at errnoException (child_process.js:988:11)
    at Process.ChildProcess._handle.onexit (child_process.js:779:34)

Probably it’d be a good idea to show some more informative error.

[dy]

#98 fixes that.
@substack please review and merge.