Pause event

Pause event test build.
Learn more from issue rocksdanister/lively#974

To enable the event per wallpaper, edit LivelyInfo.json in wallpaper folder:

  "Arguments": "--pause-event true",

and in javascript:

function livelyWallpaperPlaybackChanged(data)
{
 var obj = JSON.parse(data);
 console.log(obj.IsPaused);
}