Add tasks for all the new languages

Task/Caesar-cipher/Sidef/caesar-cipher.sidef

@@ -0,0 +1,13 @@
+func caesar(msg, key, decode=false) {
+    decode && (key = (26 - key));
+    msg.gsub(/([A-Z])/i, {|c| ((c.uc.ord - 65 + key) % 26) + 65 -> chr});
+};
+
+var msg = 'THE FIVE BOXING WIZARDS JUMP QUICKLY';
+
+var enc = caesar(msg, 10);
+var dec = caesar(enc, 10, true);
+
+say "msg: #{msg}";
+say "enc: #{enc}";
+say "dec: #{dec}";