Add tasks for all the new languages

Task/FizzBuzz/Pyret/fizzbuzz.pyret

@@ -0,0 +1,20 @@
+is-positive = _ > 0 # equivalent to lam(x): x > 0 end
+
+fun fizzbuzz(n :: Number%(is-positive)) -> String:
+  doc: ```For positive input which is multiples of three return 'Fizz', for the multiples of five return 'Buzz'.
+  For numbers which are multiples of both three and five return 'FizzBuzz'. Otherwise, return the number itself.```
+  ask:
+    | num-modulo(n, 15) == 0 then: "FizzBuzz"
+    | num-modulo(n, 3) == 0 then: "Fizz"
+    | num-modulo(n, 5) == 0 then: "Buzz"
+    | otherwise: num-to-string(n)
+  end
+where:
+  fizzbuzz(1) is "1"
+  fizzbuzz(101) is "101"
+  fizzbuzz(45) is "FizzBuzz"
+  fizzbuzz(33) is "Fizz"
+  fizzbuzz(25) is "Buzz"
+end
+
+range(1, 101).map(fizzbuzz).each(print)