Cleaned up some entities.

1) Modified device tracker entities to allow for attributes to be
overwritten with configuration data.

2) Modified ISY lights to hide brightness when off.

homeassistant/components/device_tracker/__init__.py

@@ -12,6 +12,7 @@ from datetime import timedelta
 
 from homeassistant.loader import get_component
 from homeassistant.helpers import validate_config
+from homeassistant.helpers.entity import _OVERWRITE
 import homeassistant.util as util
 import homeassistant.util.dt as dt_util
 
@@ -162,9 +163,12 @@ class DeviceTracker(object):
 
         state = STATE_HOME if is_home else STATE_NOT_HOME
 
+        # overwrite properties that have been set in the config file
+        attr = dict(dev_info['state_attr'])
+        attr.update(_OVERWRITE.get(dev_info['entity_id'], {}))
+
         self.hass.states.set(
-            dev_info['entity_id'], state,
-            dev_info['state_attr'])
+            dev_info['entity_id'], state, attr)
 
     def update_devices(self, now):
         """ Update device states based on the found devices. """

homeassistant/components/isy994.py

@@ -156,6 +156,11 @@ class ISYDeviceABC(ToggleEntity):
         attr = {ATTR_FRIENDLY_NAME: self.name}
         for name, prop in self._attrs.items():
             attr[name] = getattr(self, prop)
+            attr = self._attr_filter(attr)
+        return attr
+
+    def _attr_filter(self, attr):
+        """ Placeholder for attribute filters. """
         return attr
 
     @property

homeassistant/components/light/isy994.py

@@ -38,3 +38,9 @@ class ISYLightDevice(ISYDeviceABC):
     _attrs = {ATTR_BRIGHTNESS: 'value'}
     _onattrs = [ATTR_BRIGHTNESS]
     _states = [STATE_ON, STATE_OFF]
+
+    def _attr_filter(self, attr):
+        """ Filter brightness out of entity while off. """
+        if ATTR_BRIGHTNESS in attr and not self.is_on:
+            del attr[ATTR_BRIGHTNESS]
+        return attr