Initial contribution of the Sonos 2.0 binding

Signed-off-by: Karel Goderis <karel.goderis@me.com> (github: kgoderis)
Well, I meant as a constant in Java, so that you only have to update a single place, if Sonos decides to rename it one day. Same comment applies to all other strings you are referring to more frequently. But it is up to you where you think it makes sense to put it in a reuable constant and where you want to manually maintain the strings.