final tested fix for checking credentials

Author: anton-petrov

pymodis/downmodis.py

@@ -297,7 +297,7 @@ def __init__(self, destinationFolder, password=None, user=None, token=None,
             # token for download from password
             self.token = self.password if self.user == "token" else None
 
-        if not user and not password and not token:
+        if not self.user and not self.password and not self.token:
             raise IOError("You must provide either a token or a user and password")
 
         # set the http header