PyMySQL/PyMySQL — pull request #212 by charsyam (2014-02-10 14:34:07+00:00)
Title: change charset to lowercase

I found a bug.
in MySQLdb below code is OK.

```python
g_db=pymysql.connect(user=env["user"],
passwd=env["passwd"],
db=env["db"],
host=env["host"],
use_unicode=True,
charset='UTF8')
```

but in PyMySQL, it causes error because it has "utf8" as lowcases