Sonos : Implementation of PlayerItem


Signed-off-by: Karel Goderis <karel.goderis@me.com> (github: kgoderis)
Merge branch 'sonoplayeritem' of https://github.com/kgoderis/openhab2 into kgoderis-sonoplayeritem

Signed-off-by: Kai Kreuzer <kai@openhab.org> (github: @kaikreuzer)