added imessage app icons

StickerSlackiMessageExtension/Assets.xcassets/iMessage App Icon.stickersiconset/Contents.json

@@ -1,70 +1,83 @@
 {
   "images" : [
     {
+      "filename" : "messagesIcon58.png",
       "idiom" : "iphone",
       "scale" : "2x",
       "size" : "29x29"
     },
     {
+      "filename" : "messagesIcon87.png",
       "idiom" : "iphone",
       "scale" : "3x",
       "size" : "29x29"
     },
     {
+      "filename" : "rectIcon120.png",
       "idiom" : "iphone",
       "scale" : "2x",
       "size" : "60x45"
     },
     {
+      "filename" : "rectIcon180.png",
       "idiom" : "iphone",
       "scale" : "3x",
       "size" : "60x45"
     },
     {
+      "filename" : "messagesIcon58 1.png",
       "idiom" : "ipad",
       "scale" : "2x",
       "size" : "29x29"
     },
     {
+      "filename" : "rectIcon134.png",
       "idiom" : "ipad",
       "scale" : "2x",
       "size" : "67x50"
     },
     {
+      "filename" : "rectIcon148.png",
       "idiom" : "ipad",
       "scale" : "2x",
       "size" : "74x55"
     },
     {
+      "filename" : "messagesIcon.png",
       "idiom" : "ios-marketing",
       "scale" : "1x",
       "size" : "1024x1024"
     },
     {
+      "filename" : "rectIcon54.png",
       "idiom" : "universal",
       "platform" : "ios",
       "scale" : "2x",
       "size" : "27x20"
     },
     {
+      "filename" : "rectIcon81.png",
       "idiom" : "universal",
       "platform" : "ios",
       "scale" : "3x",
       "size" : "27x20"
     },
     {
+      "filename" : "rectIcon64.png",
       "idiom" : "universal",
       "platform" : "ios",
       "scale" : "2x",
       "size" : "32x24"
     },
     {
+      "filename" : "rectIcon96.png",
       "idiom" : "universal",
       "platform" : "ios",
       "scale" : "3x",
       "size" : "32x24"
     },
     {
+      "filename" : "rectIcon.png",
       "idiom" : "ios-marketing",
       "platform" : "ios",
       "scale" : "1x",