[TIMOB-23566] iOS: Support global tintColor

   
   // Set a global tintColor once
   Ti.UI.setTintColor("#f00");
   
   var win = Ti.UI.createWindow({backgroundColor : "#fff", title: "First Window"}); 
   var nav = Ti.UI.iOS.createNavigationWindow({window: win});
   
   var btn = Ti.UI.createButton({
       title : "Open Sub-Window (button should be red)"
   });
   
   btn.addEventListener("click", function() {
       var win2 = Ti.UI.createWindow({backgroundColor : "#fff", title: "Sub Window"}); 
       var btn2 = Ti.UI.createButton({title: "Close Sub-Window (button should be green)", tintColor: "green"});
       
       btn2.addEventListener("click", function() {
           nav.closeWindow(win2);
       });
       
       win2.add(btn2);
       nav.openWindow(win2);
   });
   
   win.add(btn);
   nav.open();