mysql timezone exception fix

 异常：

error when startup service, throw exception as following:

The server time zone value 'DST' is unrecognized or represents more than one time zone.
 You must configure either the server or JDBC driver (via the serverTimezone configuration property)
 to use a more specifc time zone value if you want to utilize time zone support.

解决方式：

1. 登录Mysql查看时区：

   登录命令 mysql -u username -p password

   查看mysql时区： show variables like '%time_zone%';

2. 查看系统时区：

   命令：date

   修改系统时区，命令 sudo dpkg-reconfigure tzdata