set the default charset to utf8 when create_table
Forgot to say that I just tested it in MySQL.
 Does this not work? https://github.com/coleifer/peewee/blob/master/peewee.py#L244
 I think that is the charset when connecting to MySQL, it doesn't specify the default charset for creating tables so when I insert Chinese words to the table, they are garbled

when create table, set the default charset to utf-8 to support more languages such as Chinese.
