Add tasks for all the new languages

Task/Anonymous-recursion/Wren/anonymous-recursion.wren

@@ -0,0 +1,12 @@
+class Fibonacci {
+    static compute(n) {
+        var fib
+        fib = Fn.new {|n|
+            if (n < 2) return n
+            return fib.call(n - 1) + fib.call(n - 2)
+        }
+
+        if (n < 0) return null
+        return fib.call(n)
+    }
+}