Complete level 13.
Fix repl does not work with vim-fireplace.

This commit modifies the project.clj file such that a name-space is
created for each of the koan files.

  This change allows vim-fireplace users to be able to use the repl from
  the editor, otherwise the repl throws an exception.
Merge remote-tracking branch 'origin/fix-repl-fireplace' into dojo3
Complete level 13.
Complete level 14.
Complete level 15.
Complete level 16.