Auth with NOSASL doesn't work in latest PyHive 0.6.1

And this did work in PyHive 0.1.8.
I use thrift 0.11.0 and thrift-sasl 0.3.0.

Consider the following code in Python 2.7:

```python
import contextlib

def checkNosasl():
from pyhive import hive
with contextlib.closing(hive.connect(host='remote_host', port=10000, auth='NOSASL')) as conn:
with contextlib.closing(conn.cursor()) as cur:
cur.execute("SELECT 1 from dual")
print cur.fetchall()



if __name__ == "__main__":
checkNosasl()

```

I run it from my machine and I connect to Hive DB that is run on another machine. **My username has nothing to do with that remote machine**.

The code above didn't work with 0.6.1 and works just fine with 0.1.8.

I tried to investigate the issue, I think it is because the following change:

At hive.py Connection._ _init_ _() method the first line is

`username = username or getpass.getuser()`

and inside the body of Connection._ _init __():

`open_session_req = ttypes.TOpenSessionReq(
client_protocol=protocol_version,
configuration=configuration,
username=username,
)`

while in 0.1.8 version this snippet is

`open_session_req = ttypes.TOpenSessionReq(
client_protocol=ttypes.TProtocolVersion.HIVE_CLI_SERVICE_PROTOCOL_V1,
configuration=configuration,
)`

It is ok to factor out client_protocol, but it is not ok to pass username _at least in_ NOSASL case. My username is not relevant.