Support using group 0 with setLightState()

[drifkin]

Currently, we can't use group 0 as a shortcut to set the light state of all lights at once.

For example the following would display an error:

api.setLightState("0", state, true).fail(displayError).done()

The error reads: Api Error: The group id '0' is not valid for this Hue Bridge.

[peter-murray]

Thanks for the pull request, but I had a major update to the library for version 0.2.0, which already removes this issue, by moving the group light status requests to a new setGroupLightState() rather than being mixed up in the setLightState() function.
The updated version of the library was publish in npmjs.org today, but it does unfortunately break the existing use of the library, but this was necessary to clean up the library to make it easier to support, the changes to users should be minor (i.e. mostly in the require calls).

[drifkin]

Great, looking forward to trying the new version out.