remove code duplication: recognition and sat_recognition

[christophmluscher]

For GmmSystem in common/setups/rasr/gmm_system.py:

Can we maybe expand this step to incorporate also sat_recognition?

E.g. have a flag in the step_args and then do smth like

recog_funktion = self.sat_recognition if step_args["sat"] else self.recognition
This way we could simplify / deduplify some code above in the run_sat_step

Originally posted by @michelwi in #33 (comment)