Use regexp to check if youtube url.

- Add basic build command.

ocaml/build.sh

@@ -0,0 +1 @@
+ocamlfind ocamlc -package netclient str.cma main.ml -o cheesebot

ocaml/main.ml

@@ -1,8 +1,10 @@
+open Http_client
+open Str
+
 (* Regexp required here *)
 let is_youtube_url url =
-  match url with
-  | "http://www.youtube.com/" -> true
-  | _ -> false;;
+  let regexp = Str.regexp "http://www.youtube.com/.+" in
+  Str.string_match regexp url 0;;
 
 (* Maybe have a list of functions and
  * iter on all the items in the list *)