Use pickle protocol 2, so pickle files will work across python 2/3

fsl/utils/settings.py

@@ -390,7 +390,7 @@ class Settings(object):
 
         try:
             with open(configFile, 'wb') as f:
-                pickle.dump(config, f)
+                pickle.dump(config, f, protocol=2)
         except (IOError, pickle.PicklingError, EOFError):
             log.warning('Unable to save {} configuration file '
                         '{}'.format(self.__configID, configFile),