Replace image_tag with lazy's one in /sotechsha[2]

Author: yasulab

app/views/login_page/index.html.haml

@@ -4,8 +4,7 @@
 
 %body
   %section
-  = image_tag "/cover.png", alt: 'CoderDojo Japan カバー画像', class: 'lazyload', loading: 'lazy', "data-src" => "/cover.png", style: 'border-radius: 0; '
-
+  = lazy_image_tag "/cover.png", alt: 'CoderDojo Japan カバー画像', style: 'border-radius: 0;'  
 
   %h1.text-center.intro-header{style: "margin-top: 40px; padding-bottom: 20px;"} ログイン
   %div{style: 'margin: 0 60px 100px'}

app/views/sotechsha_overview2_page/index.html.haml

@@ -1,6 +1,6 @@
 .container-fluid
   #top.col-md-6
-    = image_tag "sotechsha-2_book-cover.png", class: "img-responsive center-block", alt: "Scratchでつくる! たのしむ! プログラミング道場", style: "width: 90%"
+    = lazy_image_tag 'sotechsha-2_book-cover.png', class: "img-responsive center-block", alt: "Scratchでつくる! たのしむ! プログラミング道場", style: "width: 90%"
     %div{:style => "text-align: center; font-size: 19.2px;"}
       = scrivito_tag :div, @obj, :body, class: "img-responsive center-block"
   .col-md-6

app/views/sotechsha_overview_page/index.html.haml

@@ -1,6 +1,6 @@
 .container-fluid
   #top.col-md-6
-    = image_tag "sotechsha-1_book-cover.png", class: "img-responsive center-block", alt: "Scratchでつくる! たのしむ! プログラミング道場", style: "width: 90%"
+    = lazy_image_tag 'sotechsha-1_book-cover.png', class: "img-responsive center-block", alt: "Scratchでつくる! たのしむ! プログラミング道場", style: "width: 90%"
     %div{:style => "text-align: center; font-size: 19.2px;"}
       = scrivito_tag :div, @obj, :body, class: "img-responsive center-block"
   .col-md-6