Add support to change language in profile form

app/controllers/profiles_controller.rb

@@ -85,7 +85,8 @@ class ProfilesController < Profiles::ApplicationController
       :twitter,
       :username,
       :website_url,
-      :organization
+      :organization,
+      :preferred_language
     )
   end
 end

app/views/profiles/show.html.haml

@@ -73,6 +73,9 @@
         = f.select :public_email, options_for_select(@user.all_emails, selected: @user.public_email), { include_blank: 'Do not show on profile' }, class: "select2"
         %span.help-block This email will be displayed on your public profile.
       .form-group
+        = f.label :preferred_language, class: "label-light"
+        = f.select :preferred_language, Gitlab::I18n::AVAILABLE_LANGUAGES, {}, class: "select2"
+      .form-group
         = f.label :skype, class: "label-light"
         = f.text_field :skype, class: "form-control"
       .form-group

lib/gitlab/i18n.rb

+module Gitlab
+  module I18n
+    AVAILABLE_LANGUAGES = [
+      [_('English'), 'en'],
+      [_('Spanish'), 'es'],
+      [_('Deutsch'), 'de']
+    ]
+  end
+end