Fix some typos

For metadata_listen - if it's set to 127.0.0.1 I'm getting lots of errors like this when the instance is spawning:
```
2014-01-13 20:42:03.517 1856 ERROR neutron.agent.metadata.agent [-] Unexpected error.
2014-01-13 20:42:03.517 1856 TRACE neutron.agent.metadata.agent Traceback (most recent call last):
2014-01-13 20:42:03.517 1856 TRACE neutron.agent.metadata.agent   File "/usr/lib/python2.7/dist-packages/neutron/agent/metadata/agent.py", line 96, in __call__
2014-01-13 20:42:03.517 1856 TRACE neutron.agent.metadata.agent     return self._proxy_request(instance_id, req)
2014-01-13 20:42:03.517 1856 TRACE neutron.agent.metadata.agent   File "/usr/lib/python2.7/dist-packages/neutron/agent/metadata/agent.py", line 148, in _proxy_request
2014-01-13 20:42:03.517 1856 TRACE neutron.agent.metadata.agent     body=req.body)
2014-01-13 20:42:03.517 1856 TRACE neutron.agent.metadata.agent   File "/usr/lib/python2.7/dist-packages/httplib2/__init__.py", line 1444, in request
2014-01-13 20:42:03.517 1856 TRACE neutron.agent.metadata.agent     (response, content) = self._request(conn, authority, uri, request_uri, method, body, headers, redirections, cachekey)
2014-01-13 20:42:03.517 1856 TRACE neutron.agent.metadata.agent   File "/usr/lib/python2.7/dist-packages/httplib2/__init__.py", line 1196, in _request
2014-01-13 20:42:03.517 1856 TRACE neutron.agent.metadata.agent     (response, content) = self._conn_request(conn, request_uri, method, body, headers)
2014-01-13 20:42:03.517 1856 TRACE neutron.agent.metadata.agent   File "/usr/lib/python2.7/dist-packages/httplib2/__init__.py", line 1132, in _conn_request
2014-01-13 20:42:03.517 1856 TRACE neutron.agent.metadata.agent     conn.connect()
2014-01-13 20:42:03.517 1856 TRACE neutron.agent.metadata.agent   File "/usr/lib/python2.7/dist-packages/httplib2/__init__.py", line 798, in connect
2014-01-13 20:42:03.517 1856 TRACE neutron.agent.metadata.agent     raise socket.error, msg
2014-01-13 20:42:03.517 1856 TRACE neutron.agent.metadata.agent error: [Errno 111] ECONNREFUSED
```