[MOD-2145] Ti.Map: iOS - Support Image Overlays

   1. Creating image overlay -
        var imageOverlay = Map.createImageOverlay({
                                             boundsCoordinate: {
                                               topLeft:{ latitude: 34.4311, longitude: -118.6012 },
                                               bottomRight:{ latitude: 34.4194, longitude: -118.5912 },
                                             },
                                 image: 'overlay_park.png',
                                 });
   
   2. Add single image overlay -
          mapview.addImageOverlays(imageOverlay);
   
   3. Add multiple image overlay -
        mapview.addImageOverlays([imageOverlay1, imageOverlay2]);
   
   4. Remove single image overlay -
          mapview.removeImageOverlay(imageOverlay);
   
   5. Remove all image overlays -
        mapview.removeAllImageOverlays();
   
   

   var Map = require('ti.map');
   var win = Titanium.UI.createWindow();
   
   var mountainView = Map.createAnnotation({
       latitude:34.4448,
       longitude:-118.5971,
       title:"Appcelerator Headquarters",
       subtitle:'Mountain View, CA',
       pincolor:Map.ANNOTATION_RED,
       myid:1 // Custom property to uniquely identify this annotation.
   });
   
   var mapview = Map.createView({
       mapType: Map.STANDARD_TYPE,
       region: {latitude:34.4248, longitude: -118.5971,
               latitudeDelta:0.01, longitudeDelta:0.01},
       animate:true,
       regionFit:true,
       userLocation:true,
       annotations:[mountainView]
   });
   
   var imageOverlay = Map.createImageOverlay({
                                             boundsCoordinate: {
                                               topLeft:{ latitude: 34.4311, longitude: -118.6012 },
                                               bottomRight:{ latitude: 34.4194, longitude: -118.5912 },
                                             },
                                 image: 'overlay_park.png',
                                 });
   
   var imageOverlay1 = Map.createImageOverlay({
                                             boundsCoordinate: {
                                             topLeft:{ latitude: 34.4511, longitude: -118.6012 },
                                             bottomRight:{ latitude: 34.4394, longitude: -118.5912 },
                                             },
                                             image: 'image2.jpg',
                                             });
   
   mapview.addImageOverlays([imageOverlay, imageOverlay1]);
   //mapview.addImageOverlay(imageOverlay);
    setTimeout(function(e){
    Ti.API.info("inside timer");
    //mapview.removeAllImageOverlays();
   mapview.removeImageOverlay(imageOverlay);
    }, 5000);
   
   win.add(mapview);
   // Handle click events on any annotations on this map.
   mapview.addEventListener('click', function(evt) {
       Ti.API.info("Clicked " + evt.clicksource + " on " + evt.latitude + "," + evt.longitude);
   });
   win.open();