Cleanup

Moved katana.rb and katas dir out to parent directory.
Changed Kata#filename to Kata#name. E.g. "div_by_two" instead of "katas/div_by_two.rb".
Made Kata#to_s include tags.
Made routing code cleaner.
Broke attempt_controller#try into try(kata), try_random, try_specific and try_tag.
Renamed KatanaAttemptController to AttemptController, and KataFileIO to FileController.
Renamed kata_attempt_controller.rb to attempt_controller.rb and kata_io_controller to file_controller.
Accidentally added query_board kata and kept it because it's nice.
Some other small changes.