make first working version of rock paper scissors game

@gabebw @jsteiner
You should extract a constant when it is a "Unique value with unexplained meaning or multiple occurrences which could (preferably) be replaced with a named constant". The list of moves is core to how your program functions, and should be explained. The words you use to prompt the user can be changed without affecting how your program functions at all - if you write `"Move? >"` instead, nothing really changes in the logic.