add remaining assets

added correct image assets

Author: vatsalkul

Powerup/Images.xcassets/minesweeper_tutorial_1.imageset/Contents.json

@@ -2,17 +2,17 @@
   "images" : [
     {
       "idiom" : "universal",
-      "filename" : "minesweeper tutorial 1.png",
+      "filename" : "minesweeper_tutorial_1.png",
       "scale" : "1x"
     },
     {
       "idiom" : "universal",
-      "filename" : "minesweeper tutorial 1-1.png",
+      "filename" : "minesweeper_tutorial_1-1.png",
       "scale" : "2x"
     },
     {
       "idiom" : "universal",
-      "filename" : "minesweeper tutorial 1-2.png",
+      "filename" : "minesweeper_tutorial_1-2.png",
       "scale" : "3x"
     }
   ],

Powerup/Images.xcassets/minesweeper_tutorial_1.imageset/minesweeper tutorial 1-1.png

@@ -2,17 +2,17 @@
   "images" : [
     {
       "idiom" : "universal",
-      "filename" : "minesweeper tutorial 2-2.png",
+      "filename" : "minesweeper_tutorial_2.png",
       "scale" : "1x"
     },
     {
       "idiom" : "universal",
-      "filename" : "minesweeper tutorial 2-1.png",
+      "filename" : "minesweeper_tutorial_2-1.png",
       "scale" : "2x"
     },
     {
       "idiom" : "universal",
-      "filename" : "minesweeper tutorial 2.png",
+      "filename" : "minesweeper_tutorial_2-2.png",
       "scale" : "3x"
     }
   ],