Fixed DivisionByZero Exception - Power values do not change when PV Inverter is disconnected - added and new config options

[mmeintel]

• Fixed division by zero Exception when no more power is retrieved - see below
• Added possibility to override max_retries in config file
• Added possibility to override inverter_name in config file

Stacktrace

Thread: doing
requested no login
Exception in thread Thread-1:
Traceback (most recent call last):
  File "/usr/lib/python2.7/threading.py", line 801, in __bootstrap_inner
    self.run()
  File "/usr/lib/python2.7/threading.py", line 754, in run
    self.__target(*self.__args, **self.__kwargs)
  File "kostal.py", line 358, in kostal_update_cyclic
    kostal_read_data()
  File "kostal.py", line 292, in kostal_read_data
    jsonstr = kostal_v3_to_v1_json(response.json())
  File "kostal.py", line 246, in kostal_v3_to_v1_json
    data['IA'] = round(data['PA'] / float(data['VA']),1)
ZeroDivisionError: float division by zero