Add XBMC Localplay

As XBMC Localplay projects on Ampache are all dead since years (I think since the XBMC HTTP API was deprecated), I added a new XBMC Localplay plug-in.
It's a working XBMC Localplay controller with all localplay features implemented.

It uses JSON-RPC API over TCP, with xmbc-php-rpc library (https://github.com/karlrixon/xbmc-php-rpc)