Light: TSL2591 controller

[rwaldron]

@burgo4 this is all yours

[rwaldron]

Here's what's done in Light so far: https://github.com/rwaldron/johnny-five/blob/master/lib/light.js

[dtex]

Hi @rwaldron and @burgo4 ,

Johnny-Five contributors and maintainers are loathe to close issues where someone has a need. We don't want anyone to ever feel that we don't care, but we just haven't gotten to this feature yet. Rather than leave it languishing as an open issue we have created a Requested Features page and added your request for the TSL2591 there.