Does not work under Node 0.10 due to missing execSync API

@mikolalysenko
Found this thing: https://www.npmjs.com/package/sync-exec, looks like it could be worth a try.

Perhaps just check `process.version` and fall back to this module on older versions of node?

Or if this works, but is a little too ugly to add as a dependency on master, maybe we could make a `node-0.10-support` branch where we replace `execSync` with this function. We could publish that branch as a named release, e.g. `1.0.0-node0.10-support`.