报错：
Warning: mysql_connect(): mysqlnd cannot connect to MySQL 4.1+ using the
old insecure authentication. Please use an administration tool to reset your
password with the command SET PASSWORD = PASSWORD(‘your_existing_password’).
This will store a new, and more secure, hash value in mysql.user. If this user
is used in other scripts executed by PHP 5.2 or earlier you might need to remove
the old-passwords flag from your my.cnf file
解决方案：
在PHP5.3、5.4、5.5版本的情况下，有这个报错，mysql密码的加密模式设置为41位，即可
重新设置密码，密码可以和之前的一样，把加密模式改为41位