Extend youtube regexp.

Cheesebot can now recognize youtube urls formatted like this:

- http://www.youtube.com
- https://www.youtube.com
- http://youtube.com
- www.youtube.com
- youtu.be

ocaml/main.ml

@@ -14,12 +14,13 @@ Http_client.Convenience.configure_pipeline
 
 (* Regexp required here *)
 let is_youtube_url url =
-  let regexp = Str.regexp "https://www.youtube.com/.+" in
+  let regexp = Str.regexp "\\(https?\\://\\)?\\(www\\.\\)?\\(youtube\\.com\\)\\|\\(youtu\\.be\\)/.+" in
   Str.string_match regexp url 0
 
 
 let get_body url =
   try Http_client.Convenience.http_get url with
+  | Http_client.Http_error e -> "http error /o\\"
   | Failure f -> "http fail lol"