Add name-spaces to the clojure koans files.

This pull request is essentially a duplicate of #69 but without the eclipse specific entries.

I also added the `(ns koan-engine.runner)` expression to the beginning of each file (the order matters).  
This change fixes the issue in #68 (although I'm not certain how).

In order for this to work without causing failure of koan test then functional-koans/clojure-koan-engine#9
needs to be merged into the koan-engine project.