Localizations for most server-side strings

app/views/about/index.html.haml

@@ -6,24 +6,15 @@
     = image_tag 'logo.png'
     Mastodon
 
-  %p
-    Mastodon is a
-    %em free, open-source
-    social network server. A
-    %em decentralized
-    alternative to commercial platforms, it avoids the risks of a single company monopolizing your communication. Anyone can run Mastodon and participate in the
-    %em social network
-    seamlessly.
-  %p
-    %em= Rails.configuration.x.local_domain
-    is a Mastodon instance.
+  %p= t('about.about_mastodon').html_safe
+  %p= t('about.about_instance', instance: Rails.configuration.x.local_domain).html_safe
 
   .screenshot= image_tag 'screenshot.png'
 
   .actions
     .info
-      = link_to 'Terms', terms_path
-      = link_to 'Source code', 'https://github.com/Gargron/mastodon'
+      = link_to t('about.terms'), terms_path
+      = link_to t('about.source_code'), 'https://github.com/Gargron/mastodon'
 
-    = link_to 'Get started', new_user_registration_path, class: 'button'
-    = link_to 'Log in', new_user_session_path, class: 'button'
+    = link_to t('about.get_started'), new_user_registration_path, class: 'button'
+    = link_to t('auth.login'), new_user_session_path, class: 'button'