Kerberos auth Failed

```
from pyhive import hive

con = hive.Connection(host="10.8.8.8", port=21000, auth='KERBEROS', kerberos_service_name="hive")
cursor = con.cursor()
cursor.execute('show databases')
datas = cursor.fetchall()
print(datas)
```
thrift.transport.TTransport.TTransportException: Could not start SASL: b'Error in sasl_client_start (-1) SASL(-1): generic failure: GSSAPI Failure: no serverFQDN'

Debug the code in "pyhive/hive.py"
```
def sasl_factory():
sasl_client = sasl.Client()
#sasl_client.setAttr('host', serverFQDN)
if sasl_auth == 'GSSAPI':
sasl_client.setAttr('service', kerberos_service_name)
```
and find that serverFQDN should be taken as the input to hive.Connection and propagate to sasl_factory()