Remove unnecessary call to partial in second koan

juxt returns a function that takes a variable number of arguments, so a
partial taking one argument does not need to be created.
fix spacing issue in 05_maps.clj
Merge pull request #76 from mjansen401/master

fix spacing issue in 05_maps.clj
Merge pull request #74 from ajmccluskey/21-remove-partial

Remove unnecessary call to partial in second koan
Add name-spaces to the clojure koans files.

This commit adds two name-spaces to beginning of the clojure koan files
in order to fix an issue both #68 and #69.
Bump koan-engine dependency

Also eliminates some ns forms that we can do without now.

Closes #71