Allow setting of default language through config

Setting of locale in controller extracted to Localized concern,
the doorkeeper authorized applications controller moved under
custom namespace with inclusion of Localized, which resolves the
"it sometimes appears in a different random language" bug

app/views/oauth/authorized_applications/index.html.haml

@@ -0,0 +1,23 @@
+- content_for :page_title do
+  = t('doorkeeper.authorized_applications.index.title')
+
+%table.table
+  %thead
+    %tr
+      %th= t('doorkeeper.authorized_applications.index.application')
+      %th= t('doorkeeper.authorized_applications.index.scopes')
+      %th= t('doorkeeper.authorized_applications.index.created_at')
+      %th
+  %tbody
+    - @applications.each do |application|
+      %tr
+        %td
+          - if application.website.blank?
+            = application.name
+          - else
+            = link_to application.name, application.website
+        %th= application.scopes.map { |scope| t(scope, scope: [:doorkeeper, :scopes]) }.join('<br />').html_safe
+        %td= l application.created_at
+        %td
+          - unless application.superapp?
+            = table_link_to 'times', t('doorkeeper.authorized_applications.buttons.revoke'), oauth_authorized_application_path(application), method: :delete, data: { confirm: t('doorkeeper.authorized_applications.confirmations.revoke') }