More pylint 2 fixes (#15565)

## Description:

More fixes flagged by pylint 2 that don't hurt to have before the actual pylint 2 upgrade (which I'll submit soon).

## Checklist:
  - [ ] The code change is tested and works locally.
  - [x] Local tests pass with `tox`. **Your PR cannot be merged unless tests pass**

homeassistant/components/sensor/emoncms.py

@@ -190,7 +190,7 @@ class EmonCmsSensor(Entity):
             self._state = round(float(elem["value"]), DECIMALS)
 
 
-class EmonCmsData(object):
+class EmonCmsData:
     """The class for handling the data retrieval."""
 
     def __init__(self, hass, url, apikey, interval):