fix(bg): correct image to pre-load and optimized bg image

src/app/app.component.ts

@@ -58,6 +58,6 @@ export class App {
 
   private _loadImages():void {
     // register some loaders
-    BaThemePreloader.registerLoader(this._imageLoader.load(layoutPaths.images.root + 'blur-bg-mobile.jpg'));
+    BaThemePreloader.registerLoader(this._imageLoader.load(layoutPaths.images.root + 'sky-bg.jpg'));
   }
 }

src/app/theme/services/baImageLoader/baImageLoader.service.ts

@@ -8,7 +8,7 @@ export class BaImageLoaderService {
     return new Promise((resolve, reject) => {
       let img = new Image();
       img.src = src;
-      img.onload = function(){
+      img.onload = function() {
         resolve('Image with src ' + src + ' loaded successfully.');
       };
     });