Delete implementations in mythical creatures
Add skips in mythical creatures. Fixes #8
Merge pull request #9 from kytrinyx/mythical-creatures-cleanup

Mythical creatures cleanup
Add extra challenges to the Mythical Creatures for students who move quickly
Update centaur_test.rb

It appears a couple tests do not seem to be testing what they say they are testing...?
Merge pull request #11 from lukeaiken/patch-1

Update centaur_test.rb