Add redis handler to bcbio!

This PR add Redis to the logging options in bcbio. Also re-structures a little bit the logging process appending all the handlers to a NestedSetup handler, which basically will group all the handlers (so we can log in multiple places). 

Please @b97pla , take a look at this. I've already tested my branch in b5, if you check the config file for illumina_finish_msg.py you'll see the Redis parameters. 

Tack!