Major API Change : support HUE / Sat approach

[loicortola]

This issue tracks the work to be made on implementing a new API closer to the existing Zigbee Light Link standard (in HTTP though)

References include:

http://vanseodesign.com/web-design/hue-saturation-and-lightness/

https://www.developers.meethue.com/documentation/core-concepts

http://zigate.fr/wiki/commandes-zigate/

[loicortola]

The API should follow YeeLight Standards
http://www.yeelight.com/download/Yeelight_Inter-Operation_Spec.pdf