Prevent Fargo from stomping all over log settings

The logging library we use only lets us set one log backend, and sadly, Fargo's default settings stomp over mine as soon as I load it meaning I can't get debug logs.

This PR removes the init function from log.go and leaves it up to the entry point of an application to initialize the log. 

If [go-logging](https://github.com/op/go-logging) adds a way to discover if a backend is already set, we could add this block back in with a check for an existing backend.