Fixes panics on connection failures and adds retry capabilities to goworker

Instead of just crashing hard when connection to redis is not available (nil `RedisConn` pointers would be passed on to methods instead of being properly checked for nil), the lib can now keep retrying in order to survive intermittent network failures (i.e. redis connections going up and down.)
https://www.youtube.com/watch?v=MpPvGlrqhdA