Ensure meditations expressions alternate properly

Hat tip to @seriouspony for the report
Require a true result, not just a truthy one

This keeps things like (def x 2) from accidentally passing.
Bump to version 0.2.1
Clean up whitespace
Iterate over koans and add ns when init repl.

This commit adds a way to iterate over all the koans in a koans project
in a modularized way that can be handled by the koan-engine.