Don't use value of 0 for y in xy (see #171).
Ignore config attributes for daylight sensor.
Use semver for version checking.
Bump versions:
- gen1 Hue bridge to API v1.16.0;
- gen2 Hue bridge to API v1.21.0;
- deCONZ gateway to 2.04.81;
- NodeJS to v6.11.4 LTS.
Fix for homebridge/homebridge#1541 in lieu of #177.