use URL for setup

In order to make the setup of the Lamernews easier with RedisToGo, it would be nice to pass in an URL for the Redis setup, like:

    redis://redistogo:44ec0bc04dd4a5afe77a649acee7a8f3@drum.redistogo.com:9092/


The host, port _and_ password can be extracted from the URL above, and also, RedisHost and RedisPort can be removed from the config.