Sphero.start needs to actually retry on connection issues

I was having connection issues with my Sphero, and it turns out that at some point the begin in the self.start method got removed, so it wasn't actually rescuing properly if it couldn't connect.

Additionally, the retry code was only retrying *unless* the retry number was *greater* than zero.   I've changed it to a less-than, which means it actually retries now.