Use fixed sauce-connect-launcher that will not crash in spawned Node.js process

Currently, `sauce-connect-launcher` uses `progress` which does not allow forcing terminal mode in `readline`. This means that the grunt task will crash on certain platforms (Mac OS, maybe others) if Sauce Connect has not been downloaded already. I have forked both `sauce-connect-launcher` and `progress` and submitted a pull request (https://github.com/visionmedia/node-progress/pull/23) for `progress` (I'll do the same for `sauce-connect-launcher` as soon as the first one lands). This is a temporary measure until those two packages are fixed.