default and custom error pages response

+ refactoring in response.cpp (functions split)
+ added Client::clear()
+ added replace_all_substr() in utils.cpp

srcs/config/ServerConfig.hpp

@@ -30,7 +30,7 @@ public:
 	// there can only be one.
 	std::string	root;
 	
-	int			client_body_limit;	// set to default max if none set
+	unsigned int	client_body_limit;	// set to default max if none set
 
 	// might be the only one we let slide if bad input...
 	bool		autoindex;