Windows implementation fixes and improvements

1. Added {keepCallback: true} so that it can propagate several navigation events

2. "calc(100% - 80px)" style instead of onresize callback and resizing manually

3. I think it is better to use cordova.platformId to detect modern Windows version instead of Api below which is subject for changes in the future - Scheduler.schedule could be renamed in the future

    isWinJS2 = !!WinJS.Utilities.Scheduler && !!WinJS.Utilities.Scheduler.schedule