Removes outdated rel='image_src'

Replaces that with new Open Graph meta tags.
Closes #2335.

Author: gnclmorais

app/views/errors/error.html.haml

@@ -1,7 +1,7 @@
 !!!
 %html
   %head
-    %link{ rel: 'image_src', href: '/assets/logo-square.png', :alt => "codebar logo" }
+    = render partial: 'meta_tags'
     = favicon_link_tag 'favicon.ico'
     %title codebar.io - Page not found
     :css

app/views/errors/not_found.html.haml

@@ -1,7 +1,7 @@
 !!!
 %html
   %head
-    %link{ rel: 'image_src', href: '/assets/logo-square.png', :alt => "codebar logo" }
+    = render partial: 'meta_tags'
     = favicon_link_tag 'favicon.ico'
     %title codebar.io - Page not found
     :css

app/views/layouts/_meta_tags.html.haml

@@ -0,0 +1,9 @@
+%meta{ property: 'og:title', content: 'codebar' }
+%meta{ property: 'og:type', content: 'website' }
+%meta{ property: 'og:url', content: request.original_url }
+%meta{ property: 'og:image', content: image_url('logo-square.png') }
+%meta{ property: 'og:description', content: 'Making tech more diverse and welcoming by bringing people together and helping teach programming skills.' }
+%meta{ property: 'og:site_name', content: 'codebar' }
+%meta{ property: 'og:locale', content: 'en_GB' }
+-# Only Twitter-specific tag needed
+%meta{ name: 'twitter:card', content: image_url('logo-square.png') }

app/views/layouts/application.html.haml

@@ -10,21 +10,12 @@
 
     - if content_for? :meta_tags
       = yield :meta_tags
-    - else 
-      %meta{ property: 'og:title', content: 'codebar' }
-      %meta{ property: 'og:type', content: 'website' }
-      %meta{ property: 'og:url', content: request.original_url }
-      %meta{ property: 'og:image', content: image_url('logo-square.png') }
-      %meta{ property: 'og:description', content: 'Making tech more diverse and welcoming by bringing people together and helping teach programming skills.' }
-      %meta{ property: 'og:site_name', content: 'codebar' }
-      %meta{ property: 'og:locale', content: 'en_GB' }
-      -# Only Twitter-specific tag needed
-      %meta{ name: 'twitter:card', content: image_url('logo-square.png') }
+    - else
+      = render partial: 'layouts/meta_tags'
 
     %link{ rel: 'icon', sizes: '196x196', href: '/Icon-196.png'}
     %link{ rel: 'icon', sizes: '128x128', href: '/Icon-128.png'}
     %link{ rel: 'apple-touch-icon', sizes: '128x128', href: '/Icon-128.png'}
-    %link{ rel: 'image_src', href: '/assets/logo-square.png', alt: 'codebar logo' }
 
     %title= retrieve_title
     = favicon_link_tag 'favicon.ico'