Update iOS App Icon to the new single-size format (#573)

bitchat/Assets.xcassets/AppIcon.appiconset/Contents.json

@@ -1,111 +1,9 @@
 {
   "images" : [
-    {
-      "filename" : "icon_20x20@2x.png",
-      "idiom" : "iphone",
-      "scale" : "2x",
-      "size" : "20x20"
-    },
-    {
-      "filename" : "icon_20x20@3x.png",
-      "idiom" : "iphone",
-      "scale" : "3x",
-      "size" : "20x20"
-    },
-    {
-      "filename" : "icon_29x29@2x.png",
-      "idiom" : "iphone",
-      "scale" : "2x",
-      "size" : "29x29"
-    },
-    {
-      "filename" : "icon_29x29@3x.png",
-      "idiom" : "iphone",
-      "scale" : "3x",
-      "size" : "29x29"
-    },
-    {
-      "filename" : "icon_40x40@2x.png",
-      "idiom" : "iphone",
-      "scale" : "2x",
-      "size" : "40x40"
-    },
-    {
-      "filename" : "icon_40x40@3x.png",
-      "idiom" : "iphone",
-      "scale" : "3x",
-      "size" : "40x40"
-    },
-    {
-      "filename" : "icon_60x60@2x.png",
-      "idiom" : "iphone",
-      "scale" : "2x",
-      "size" : "60x60"
-    },
-    {
-      "filename" : "icon_60x60@3x.png",
-      "idiom" : "iphone",
-      "scale" : "3x",
-      "size" : "60x60"
-    },
-    {
-      "filename" : "icon_20x20.png",
-      "idiom" : "ipad",
-      "scale" : "1x",
-      "size" : "20x20"
-    },
-    {
-      "filename" : "icon_20x20@2x.png",
-      "idiom" : "ipad",
-      "scale" : "2x",
-      "size" : "20x20"
-    },
-    {
-      "filename" : "icon_29x29.png",
-      "idiom" : "ipad",
-      "scale" : "1x",
-      "size" : "29x29"
-    },
-    {
-      "filename" : "icon_29x29@2x.png",
-      "idiom" : "ipad",
-      "scale" : "2x",
-      "size" : "29x29"
-    },
-    {
-      "filename" : "icon_40x40.png",
-      "idiom" : "ipad",
-      "scale" : "1x",
-      "size" : "40x40"
-    },
-    {
-      "filename" : "icon_40x40@2x.png",
-      "idiom" : "ipad",
-      "scale" : "2x",
-      "size" : "40x40"
-    },
-    {
-      "filename" : "icon_76x76.png",
-      "idiom" : "ipad",
-      "scale" : "1x",
-      "size" : "76x76"
-    },
-    {
-      "filename" : "icon_76x76@2x.png",
-      "idiom" : "ipad",
-      "scale" : "2x",
-      "size" : "76x76"
-    },
-    {
-      "filename" : "icon_83.5x83.5@2x.png",
-      "idiom" : "ipad",
-      "scale" : "2x",
-      "size" : "83.5x83.5"
-    },
     {
       "filename" : "icon_1024x1024.png",
-      "idiom" : "ios-marketing",
-      "scale" : "1x",
+      "idiom" : "universal",
+      "platform" : "ios",
       "size" : "1024x1024"
     },
     {