XBMC - Add binding option to use 'Player.open' RPC call.

Use this in combination with a String item and a sendCommand call in your rules. The string should be set to the URL that XBMC needs to open.
Merge pull request #1348 from avdleeuw/xbmx-playeropen

XBMC - Add binding option to use 'Player.open' RPC call.