Correct two files to be inline with pep8 standards.

pytac/exceptions.py

@@ -1,24 +1,29 @@
 """Module containing all the exceptions used in pytac."""
 
+
 class FieldException(Exception):
     """Exception associated with invalid field requests.
     """
     pass
 
+
 class HandleException(Exception):
     """Exception associated with requests with invalid handles.
     """
     pass
 
+
 class DeviceException(Exception):
     """Exception associated with Device misconfiguration or invalid requests.
     """
     pass
 
+
 class UnitsException(Exception):
     """Conversion not understood
     """
     pass
 
+
 class LatticeException(Exception):
     pass

pytac/model.py

@@ -2,6 +2,7 @@
 import pytac
 from pytac.exceptions import FieldException
 
+
 class Model(object):
     """Abstract base classes for element models.