On adding Group / List support to #AndStatus

@rozzin  After today's thinking about our discussion and re-reading of the thread, I seem like understand, what needs to be done, see updated comment:
https://github.com/andstatus/andstatus/issues/248#issuecomment-219826572
And what's interesting: GNU Social's groups look like the first to be worth implementing. Simply because they work and at least somebody is using them, I hope.

Or it is too late to implement something for #GNUSocial ?!
I mean, too few people use it..?!