Update token request with new scope parameter

Due to Netatmo API change, a new "scope" parameter is required for client authentication.
scope is requested with "read_station" value. This is the only scope currently supported in this library. Other scope values are related to thermostat management (I don't have one, I can't test anything thus I will not try to develop in the blind.) Contributions are welcome.

Appart from new API compliance, no change has been introduced in usage.

lnetatmo.py

@@ -70,7 +70,8 @@ def __init__(self, clientId=_CLIENT_ID,
                 "client_id" : clientId,
                 "client_secret" : clientSecret,
                 "username" : username,
-                "password" : password
+                "password" : password,
+                "scope" : "read_station"
                 }
         resp = postRequest(_AUTH_REQ, postParams)