remove backgrounds of all slides

slides/list.json

@@ -2,103 +2,100 @@
     {
         "filename": "index.md",
         "attr": {
-            "data-background": "img/sbgBackgroundWhite.jpg"
         }
     },
     {
         "filename": "overview.md",
         "attr": {
-          "data-background": "img/whiteBG.jpg"
         }
     },
     {
         "filename": "the_terminal.md",
         "attr": {
-          "data-background": "img/whiteBG.jpg"
         }
     },
     {
         "filename": "the_editor.md",
         "attr": {
-          "data-background": "img/whiteBG.jpg"
+
         }
     },
     {
         "filename": "what_is_git.md",
         "attr": {
-          "data-background": "img/whiteBG.jpg"
+
         }
     },
     {
         "filename": "installation.md",
         "attr": {
-          "data-background": "img/whiteBG.jpg"
+
         }
     },
     {
         "filename": "github_gitlab.md",
         "attr": {
-          "data-background": "img/whiteBG.jpg"
+
         }
     },
     {
         "filename": "configuration.md",
         "attr": {
-          "data-background": "img/whiteBG.jpg"
+
         }
     },
     {
         "filename": "cloneRepo.md",
         "attr": {
-          "data-background": "img/whiteBG.jpg"
+
         }
     },
     {
         "filename": "forks.md",
         "attr": {
-          "data-background": "img/whiteBG.jpg"
+
         }
     },
     {
         "filename": "branches.md",
         "attr": {
-          "data-background": "img/whiteBG.jpg"
+
         }
     },
     {
         "filename": "essential_commands.md",
         "attr": {
-          "data-background": "img/whiteBG.jpg"
+
         }
     },
     {
         "filename": "merge.md",
         "attr": {
-          "data-background": "img/whiteBG.jpg"
+
         }
     },
     {
         "filename": "syncFork.md",
         "attr": {
-          "data-background": "img/whiteBG.jpg"
+
         }
     },
     {
         "filename": "best_practices.md",
         "attr": {
-          "data-background": "img/whiteBG.jpg"
+
         }
     },
     {
         "filename": "homework.md",
         "attr": {
-          "data-background": "img/whiteBG.jpg"
+
         }
     },
     {
         "filename": "thanks.md",
         "attr": {
-          "data-background": "img/whiteBG.jpg"
+
         }
     }
 ]