Clojurians Log v2

@richiardiandrea @alexyakushev @alandipert At the time it had little use but I keep coming back to a spec based DSL

https://github.com/boot-clj/boot/issues/667

If I were going to go at this again I would probably base it off something like http://github.com/degree9/covenant

The problem is generally that you are not only validating the options but then converting them from strings, covenant could do the former but a solution for the latter would still be needed